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Any downside to duals dumped before the axle?

This is a discussion on Any downside to duals dumped before the axle? within the External Engine forums, part of the LSx Technical Help Section category; Just wondering if true duals dumped before the axle present any disadvantages for a frequently driven car....

  1. #1
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    Any downside to duals dumped before the axle?

    Just wondering if true duals dumped before the axle present any disadvantages for a frequently driven car.

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    Member C&Cbird's Avatar
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    Other than the fact it is pretty loud that way, no disadvantages that I know of. I've seen a lot of cars with them dumped like that.

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    Moderator Firebirdjones's Avatar
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    Hmmmm,,,there are alot of disadvantages in my eyes,,,but as most other ideas about this subject,,,this is really personal opinion.

    For one,,,,I think it ruins the resale value of the car. No way would I purchase an F body with this setup, no matter how cheap the car was. Just looks tacky in my opinion,,,,the car is not designed for it. It also tells me the owner didn't want to spend the money to put a nice complete system on the car,,,,,so what other corners were cut in modifying the car? Kinda makes me think about it a little.

    Referring back to the statement of not being designed for it,,,there is not enough floor pan clearance to tuck a pair of mufflers in front of the rearend. So it hangs down and just looks like ass from behind. Taking a clean looking car and having exhaust hanging down just kills the car for me.

    Another reason is,,,,why do it? There are many excellent cat back systems out there that will function as well, and still keep great ground clearance, is not visable or hanging down too low,,,,and keeps the noise level and interior resonance to a minimum including the Bassani true dual system that goes out to the rear bumpers and uses a muffler in the stock location. I nice alternative would be the Mufflex single system in 3 1/2 or even 4 inch piping.

    The noise level will be considerable inside and outside the car with a system dumped in front of the rearend....With GM spending so much time making these cars ride smooth, quiet, comfy,,,etc....why would anyone want to ruin that? It's what makes these cars so nice to drive. "shrug"

    Don't get me wrong,,,,I have done this type of setup on some old hotrods for a while,,,,but I'm getting older, and quite frankly if you have a decent motor under the hood this type of exhaust system will rattle your cage inside the car,,,and gets old, especially when the wife and kids go for a ride and start dreading the fact that I am getting it out of the garage for a drive.

    For a toy car it would be okay,,,,a daily driver, especially a plush 4th gen F-body,,,,I personally wouldn't do it.

    A better way in my opinion would be to install a nice catback system, Bassanni, Mufflex, there are many,,,,and later on if you go with long tube headers and a nice off road Y-pipe you could always install a pair of cutouts in the Y-pipe,,,and when you want to be loud and have the advantage of free flowing duals,,,,open the cutouts. You can have both at the flip of a switch if you go with electric cutouts.

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    Member C&Cbird's Avatar
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    You can also do duals over the rearend. It can be done, I've seen it many times.

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    Moderator Firebirdjones's Avatar
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    Quote Originally Posted by C&Cbird View Post
    You can also do duals over the rearend. It can be done, I've seen it many times.
    Yes you can,,,,and I have done this on a Monza (same chassis design as the 3rd and 4th gen Fbodies)

    It was all custom fabbed,,,and wasn't cheap. I only went this option because no one made a pre bent system for this car.

    Since Bassani makes one for the Fbodies I would just go this route and save the hassle.

    Plus if you are as picky as me,,,,you would have to find a shop that has a mandrel bender,,,,and thats not always easy,,,,since we are talking about a $30,000 machine that most shops won't spring for.

    A custom bent setup will most likely be crush bends. And with the really tight bends that need to be made,,,,well,,,,it's up to you

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    Quote Originally Posted by Firebirdjones View Post
    Hmmmm,,,there are alot of disadvantages in my eyes,,,but as most other ideas about this subject,,,this is really personal opinion.

    For one,,,,I think it ruins the resale value of the car. No way would I purchase an F body with this setup, no matter how cheap the car was. Just looks tacky in my opinion,,,,the car is not designed for it. It also tells me the owner didn't want to spend the money to put a nice complete system on the car,,,,,so what other corners were cut in modifying the car? Kinda makes me think about it a little.

    Referring back to the statement of not being designed for it,,,there is not enough floor pan clearance to tuck a pair of mufflers in front of the rearend. So it hangs down and just looks like ass from behind. Taking a clean looking car and having exhaust hanging down just kills the car for me.

    Another reason is,,,,why do it? There are many excellent cat back systems out there that will function as well, and still keep great ground clearance, is not visable or hanging down too low,,,,and keeps the noise level and interior resonance to a minimum including the Bassani true dual system that goes out to the rear bumpers and uses a muffler in the stock location. I nice alternative would be the Mufflex single system in 3 1/2 or even 4 inch piping.

    The noise level will be considerable inside and outside the car with a system dumped in front of the rearend....With GM spending so much time making these cars ride smooth, quiet, comfy,,,etc....why would anyone want to ruin that? It's what makes these cars so nice to drive. "shrug"

    Don't get me wrong,,,,I have done this type of setup on some old hotrods for a while,,,,but I'm getting older, and quite frankly if you have a decent motor under the hood this type of exhaust system will rattle your cage inside the car,,,and gets old, especially when the wife and kids go for a ride and start dreading the fact that I am getting it out of the garage for a drive.

    For a toy car it would be okay,,,,a daily driver, especially a plush 4th gen F-body,,,,I personally wouldn't do it.

    A better way in my opinion would be to install a nice catback system, Bassanni, Mufflex, there are many,,,,and later on if you go with long tube headers and a nice off road Y-pipe you could always install a pair of cutouts in the Y-pipe,,,and when you want to be loud and have the advantage of free flowing duals,,,,open the cutouts. You can have both at the flip of a switch if you go with electric cutouts.
    hmmmm well I guess its all personnel opinion, im 20 and have no kids and no wife and I cant get an exhaust loud enough. so I think it really depends on what your looking for....tsp true duals going in soon woo hoo!

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    Personally, I would love to have true-duals dumped. Not a lot of cars have them, at least around here. They are different, unique to most, and offer acceptional power gains over a y-pipe setup with all else being the same. Go for it if you want it. Its not like you can't change later if you ultimately don't like it.

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    Member ApexVIII's Avatar
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    its really loud lol
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    Sarge for AAG Emperor hutch1999's Avatar
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    I think they look cool and sound awesome but once again im just a young punk with no kids or a wife and complete disreguard for the law when it comes to loud exhaust.

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    Quote Originally Posted by hutch1999 View Post
    I think they look cool and sound awesome but once again im just a young punk with no kids or a wife and complete disreguard for the law when it comes to loud exhaust.
    sounds like me...TD Ftw!

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    I love mine. People are constantly telling me my car looks bad ass when they are driving behind me. Gives it more of a beefy look to me. You can ask any of my buddys with ls1's and they will tell you my exhaust set up looks and sounds the best. I ran it all the way back and ended up taking it off and dumping it. Grotyohann Ceramic Long tubes, H-pipe, delta flows, works very well for me and the exhaust being dumped gives the exhaust more of an echo sound that truly sounds alot better than running it out in my opinion.

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    The only downside in my opinion is cops will hate you, but hey we all know they already do so do something to really piss them off.

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    Sarge for AAG Emperor hutch1999's Avatar
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    fuck the police

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    Thanks for all the replies.

    Quote Originally Posted by T-56SLPSS View Post
    I ran it all the way back and ended up taking it off and dumping it.
    Did you notice any extra interior noise/vibration when you went from tailpipes to dumps? Or was it just louder in general? I like loud

    Also, no one mentioned damage to the underside of the vehicle from the exhaust gasses -- is that a non-issue?

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    yea there is more interior noise but i like it. Mine dont dump down just the 3in straight piece off the end of the delta flow. It sounds great when you first start it up and gives the car a more powerful sound while driving, not the rattle of things i had when i had cut outs on my lt1 just a nice loud rumble and as of now i have no added vibration from doing this and the under side of my car is squeeky clean. Getting ready to drop a 9in in the rear with 4.10's so ill probably give the underside a bath while im down there. You dont really have to worry about the underside of your car getting dirty unless your car is running to rich which isn't very likely to happen with the ignition set up on a ls1. They are hot firing cars and anyone who has changed spark plugs on a ls1 knows the spark is hot and if you burn it all up in the chamber you dont have to worry about it resonating all over your car.
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    I have the dumped duals before the axle, here's my summary.


    They look O.K. I don't particularly care for the appearance because I think it looks rigged. I would much rather have a nice clean chrome exhaust that exits out the back like every other vehicle on the road. One, because it wont be so obvious to police that I'm lacking cats. Two, it will drive the sound away from the cab rather than into the cab. I have a wife&child, so go figure.

    They sound AMAZING. Very Deep sound, transfers more energy to the ground which creates the deeper note and shakes the ground slightly. It reminds me of those huge double engine boats you hear chugging around the bays and marina's of yore. I like that aspect. You can feel the exhaust in your seat, and about everywhere else in the car. If you retire your head to the headrest, you will have blurred vision due to the seismic waves if your sitting idle. Once the car starts to move, you can feel the seismic waves flex throughout the vehicle as the RPM's increase. It's really cool for about a month. After that, I was starting to get annoyed. The best thing I've done with it was going through parking garages and setting off car alarms on the level below while I idle. I didn't even have to rev it up; actually revving it up reduces the amount of low wave frequency produced and defeats the alarm setting purpose originally intended.


    Pain in the ASS when navigating speed bumps (Bottomed out and now their lopsided) I was touring at Saddlebrook when I hit a speed bump too fast and bottomed out on my muffler. Now it sits 1/4 of an inch higher than the driver side muffler. Not that big of a deal to most, but I run a CAD business; I see those things and it drives me nuts.

    Performance is good, I feel that the motor can breathe easier and therefore it rev's out faster. I've got a CAM&Valve kit, so the flow really matters. I don't really like the CAM sound out of it, b/c its aimed down and the bass is all that resonates; you don't get much cam lobe or hear the chatter of the valves.


    Overall, I'm currently looking to get out of the dual dumped exhaust setup b/c its bent. It's an excuse to get new, so I'm going to try either over or under the axle duals. I'm considering the 4" pipe, but I don't know much about how it sounds or performs. Time for DD!

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    Moderator Firebirdjones's Avatar
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    Quote Originally Posted by eautocad View Post
    I have the dumped duals before the axle, here's my summary.


    They look O.K. I don't particularly care for the appearance because I think it looks rigged. I would much rather have a nice clean chrome exhaust that exits out the back like every other vehicle on the road. One, because it wont be so obvious to police that I'm lacking cats. Two, it will drive the sound away from the cab rather than into the cab. I have a wife&child, so go figure.

    They sound AMAZING. Very Deep sound, transfers more energy to the ground which creates the deeper note and shakes the ground slightly. It reminds me of those huge double engine boats you hear chugging around the bays and marina's of yore. I like that aspect. You can feel the exhaust in your seat, and about everywhere else in the car. If you retire your head to the headrest, you will have blurred vision due to the seismic waves if your sitting idle. Once the car starts to move, you can feel the seismic waves flex throughout the vehicle as the RPM's increase. It's really cool for about a month. After that, I was starting to get annoyed. The best thing I've done with it was going through parking garages and setting off car alarms on the level below while I idle. I didn't even have to rev it up; actually revving it up reduces the amount of low wave frequency produced and defeats the alarm setting purpose originally intended.


    Pain in the ASS when navigating speed bumps (Bottomed out and now their lopsided) I was touring at Saddlebrook when I hit a speed bump too fast and bottomed out on my muffler. Now it sits 1/4 of an inch higher than the driver side muffler. Not that big of a deal to most, but I run a CAD business; I see those things and it drives me nuts.

    Performance is good, I feel that the motor can breathe easier and therefore it rev's out faster. I've got a CAM&Valve kit, so the flow really matters. I don't really like the CAM sound out of it, b/c its aimed down and the bass is all that resonates; you don't get much cam lobe or hear the chatter of the valves.


    Overall, I'm currently looking to get out of the dual dumped exhaust setup b/c its bent. It's an excuse to get new, so I'm going to try either over or under the axle duals. I'm considering the 4" pipe, but I don't know much about how it sounds or performs. Time for DD!
    Referring to your last paragraph,,,going under the axle is not a good idea,,,,when it comes time for any rearend work, dropping the gas tank etc....this will cause major issues,,,and also major ground clearance problems,,,even more so than you have now.

    Your exhaust would have to hang under the axle tubes pretty far to allow the rearend to move freely,,,,this will look Horrifying from behind. Reminds me of beater pieces of junk running around that people can't afford exhaust for or the car just isn't worth it,,,so they wire tie up a bunch of flex pipe from the local auto chain store and run it under the rearend

    On a more serious note though,,,,if you are considering the 4 inch mufflex system (you mentioned 4 inch piping) I love this system,,,,too bad it's not mentioned much here,,,,it's very effective,,,I have personally seen a handfull of street driven 10 second F-bodies naturally asperated running through this system,,,,,,it works. It would be my first choice for a serious street thumper.

    Buddy of mine has a 96 LT1 with a lingenfelter 355/6 speed with the mufflex 4 inch system and flowmaster muffler,,,on drag radials and spinning like mad it runs easy 11.60's at 119 mph. There is more in the car but what is really cool is seeing this massive sewer pipe when you look under the car,,,and when he fires this thing up in the middle of 500 other cars at a local cruise in,,,,people jump up and look around. It has a sound all it's own.

    With all the single pipe cat back systems I have tried as well as this guy,,,over the years,,,it's the only system that actually made an improvement in ET and mph over the other single style systems and muffler combos. We would love to see how the Bassani true dual system compares to this 4 inch single mufflex system,,,,but can't get over the cost from an exhaust comparison standpoint. I would hate to spend a grand on Bassani and not pick anything up with the car at the track over the mufflex system,,,,but then again I hate to think what I have spent on exhaust over the last few years trying different stuff,,,,it would have paid for a Bassani setup 4 times over,,,,yikes.

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    i love mine dumped, and i can hear my radio and phone still

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    Quote Originally Posted by Firebirdjones View Post
    We would love to see how the Bassani true dual system compares to this 4 inch single mufflex system,,,,but can't get over the cost from an exhaust comparison standpoint. I would hate to spend a grand on Bassani and not pick anything up with the car at the track over the mufflex system,,,,but then again I hate to think what I have spent on exhaust over the last few years trying different stuff,,,,it would have paid for a Bassani setup 4 times over,,,,yikes.
    My thing with duals over a single is a sound thing. I had a 5.0 Mustang with cam/heads/intake, headers, off road h- pipe and 1-chambers. The sound was orgasmic. I haven't heard a single-pipe system that can compare with true duals. So for me personally, I would give up a pony or two to get that sound that I NEVER get tired of hearing every day

  20. #20
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    there's a harmony of duals that you can't get with the single pipe split.. I really want to go true dual over the axle; that's what I recommend. I like the harmony of the dual pipe setup, its a sound you can only get with duals. 4 Inch pipe does sound swell, but I'm afraid that it won't produce that symphony of pipes I'm looking for.

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