This is a discussion on Franken Mufflers within the GTO forums, part of the Vehicle Specific category; I don't know if any of you have seen the inside of the 05+ mufflers but I can tell you ...
04-30-2008, 08:33 PM #1
I don't know if any of you have seen the inside of the 05+ mufflers but I can tell you this, from chamber 2 to chamber 3 (of 5)there is a hole less than a half an inch in diameter and a bypass pipe to chamber 4 which is right at a half an inch on the driver side. The passenger side is a tad different as the chamber wall going into chamber 3 (with the half inch holes) there are about 20 small perforations (less than 1/16th diameter) going into chamber 3. Both then go through the fiberglass into a 2 in pipe via perforations in the side of it then into chamber 4 as well as back into chamber 1. It then has about a 2 inch hole leading out of the muffler (bypassing 5) with another 2 inch hole going into chamber 5 over the exit pipe. I cut open my mufflers and removed the chamber walls going into 3 and 4 (the very restrictive ones) leaving a big center chamber (over half the length of the muffler itself) and the 2 on the ends which are bypassed anyway. Flow is pretty much straight through since chamber one is bypassed on entry and the exit is directly in line with the entry tube (you can see straight through it). Just a tad bit louder at idle and normal drive and quite a bit louder WOT (not loudmouth loud though more like flow 40's). I can barely tell a difference inside the car at all idle, driving, or WOT no drone. A bit more popping letting off the gas in the higher RPM's but not bad at all. It is late so I don't have pics of the chamber walls at this moment but I will try to post them along with a video of the sound. 0 money invested fairly easy and my butt dyno tells me it is a bit of a difference over stock. Noticed my mpg avg go up a bit as well. Good sound but not obnoxious at all. I can rev to 3k and not wake the neighbors, gets a lil louder after that. I can post the best way to do it if anyone is interested but I'm sure most of you have aftermarket exhausts anyway.
05-01-2008, 04:38 AM #2
- Join Date
- Nov 2005
- Royal Oak, Michigan
- 2004 GTO A4
How did you close the mufflers once you cracked them open?
05-01-2008, 05:11 AM #3
Im guessing with a welder.
05-01-2008, 09:21 AM #4
Yes I mig welded them back together.
05-01-2008, 09:55 AM #5
I have thrown at least 6 pairs of them in the scrap metal pile in the past couple years...... LOLDon't be afraid of the bottle!!! Be afraid of your tune!!!
05-01-2008, 09:22 PM #6
I didn't take any pics during the process as I wasn't sure if it would even work at first. I do have pics of the parts removed showing how restrictive it is and now a video of it but I wil have to try to post it in the next couple of days. Pics of the mufflers would do no good as the first one I cut the side open not knowing what the inside looked like so it has a huge area of welding and filling in because of the gaps.
First unbolt the two 15mm bolts holding each muffler and remove them of course. The best way of doing it, after doing it the wrong way first (cutting the side of the muffler open causes alot of problems), is to cut the tailpipe end of the muffler completely off about 4 1/2 inches from the end (measured from the side not tailpipe you can tap it and tell where the wall is to make sure) into chamber 4 which is empty. Preferrably with a sawzall or jigsaw as the outside is comprised of 2 ply thin metal and using an cut off tool separated the two making it much harder to weld back without melting it. Once the end of the muffler is off set it aside and look into the muffler, you will be staring at the wall separating chamber 3 and 4 which will have the 2 inch pipe and 1/2 inch pipe going into 4 it but not protruding through it. This is connected to the chamber 3 wall by both pipes and will bring the two out together in one piece. I used a 3 lb hammer and just gave it a few taps straight inward to loosen them up. I then turned the muffler around looking into the intrance pipe. You will see a solid wall with no holes on the driver side and one with the small perforations on the passenger side. I took a piece of pipe about 2 foot long into the entrance pipe against the wall you see in there and hammered it until the two chambers came out together along with all the fiberglass that is inbetween them. The tap from the other side just loosened the walls now you are actually pulling the 2 inch pipe out of the 1st chamber wall which it is pressed into. After several taps the two walls and entire 3rd chamber with the pipe leading back into chamber one came out.
Reassembly, learning from the first one that if the two plys on the outside separated during cutting tack them together before you start welding. if they are separated you will be welding one ply which will burn through even on the lowest setting real easy. Mate the two and weld as you would sheetmetal on a car by just tacking all around then start overlapping the tacks. Do not try to make a bead until all your tacks are close as you will birn through. This was the hardes and most time consuming of the whole process. Once done you can look into the muffler and see straight through it and it will bolt right up. I'm not a pro welder by any means and I managed to do it with no leaks so anyone proficient with a welder can do it just be careful as it is thin.
I'll try to post the pics and video of the exhaust clip tomorrow. I'm loving the hollow grumble that it has without being really loud at all. Best of all I know it breathes alot better and can definately feel it.
05-02-2008, 03:51 PM #7
A vid of the sound is here. http://s117.photobucket.com/albums/o...BlackBetty.flv . Video quality isnt hot as I was going for audio not video but the sound is good.
Brother threw the other parts away but that just shows what corks it the big 2" pipe at the top is impassable from that chamber.
05-02-2008, 07:32 PM #8
WHOA!! Black Betty... Thats sweet man. Im definitely gonna try that on my stock 06, once I get my thermostat and suspension problems taken care of. Any noticeable difference in torque around the low end?
05-03-2008, 05:16 PM #9
Yes that was the first thing I noticed. Soon as I let off the clutch it was obvious.
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