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removing cats on a modded already tuned car?

This is a discussion on removing cats on a modded already tuned car? within the External Engine forums, part of the LSx Technical Help Section category; I bought a TA with cam,ported heads, LTs, and a catted Y-pipe i want to remove cats this spring and ...

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    Member devildogws6's Avatar
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    removing cats on a modded already tuned car?

    I bought a TA with cam,ported heads, LTs, and a catted Y-pipe i want to remove cats this spring and curious if it will affect the perfomance? Or just throw a check engine light?

    I tried to research.

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    Moderator 98TransAmWs-6's Avatar
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    You will most likely pick up a couple of hp by removing the cats as well as throwing a code unless the code has been tuned out. You may get a stronger exhaust smell as well.
    1998 Trans Am WS6 - Phantom
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    Moderator Firebirdjones's Avatar
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    Just need to tune out the rear 02's (if they haven't been already).

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    Moderator 35th-ANV-SS's Avatar
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    I posted in your other thread about this and am in agreement with the above 2 posts.

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    Member devildogws6's Avatar
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    well i would wait to do the tune till i add or change engine seeing that a tune cost $400+ unless a local mechanic could do that?

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    Moderator 35th-ANV-SS's Avatar
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    A mail-order tune from Frost is $150 and he could do that for you as well as other adjustments. You may have a local shop that is familiar with LS1's and have a hand-held tuner for them. This can be used as well I believe to tune out the rear 02's. The cost of that though may be around the same as what Frost charges and you will get more bang for your buck with Frost's mail-order tune.

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    Moderator Firebirdjones's Avatar
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    Hard money to swallow to just simply turn off the 02's (codes). Takes longer to fire up the laptop than it does to turn them off.

    Unfortunately to get any tuner to do it that hasn't tuned the car before will cost them a couple credits ($50 last time I checked) unless they have the unlimited (aka: expensive) version. Would be best to take the car to the previous tuner since they will have the file linked to your car already on hand. Takes a whole 2 minutes to shut the rear 02's off. Buy em' lunch and call it done if they are decent people to deal with.

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    Member devildogws6's Avatar
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    The place is a 6 hr drive one way to where is was last tuned I do have the reciept from when work was done suppose i can call and ask.

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    Moderator Firebirdjones's Avatar
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    Quote Originally Posted by devildogws6 View Post
    The place is a 6 hr drive one way to where is was last tuned I do have the reciept from when work was done suppose i can call and ask.
    Well, it's either that or pay Frost $150 for a mail order tune, which also requires you pull the computer and ship it to him (doesn't take long).

    Or pay $4-$500 for someone local to go through and dyno/tune session, or maybe they would be kind enough to delete the rear 02's if you talk nice for a nominal fee

    Or, buy the HPtuner software for about $600 and do anything you please to the car infinantly.

    Either way it sounds like you're in a pickle. Aren't computer controlled cars lovely?

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    Member devildogws6's Avatar
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    Yes just so lovely Haha maybe I will hold off

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    Just get a set of O2 sims , they'll run you about $100 (new).

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    Moderator 98TransAmWs-6's Avatar
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    Quote Originally Posted by Blue28 View Post
    Just get a set of O2 sims , they'll run you about $100 (new).
    Might as well get a mail order tune at that point. It is only $50 more.

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    OP: What kind of cats are on the car now? If you have a set of high flow aftermarket cats, you are not going to gain a whole bunch deleting them.

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    Member devildogws6's Avatar
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    To be honest i do not know because i didnt put them on, its a catback system i think maybe borla....so i am assuming its high flow, im going for louder the car is quiet in my opinion.

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    How about adding a cutout? Best of both worlds.

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    Member devildogws6's Avatar
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    Yeah i was thinking of doing that, but i may change up all exhaust i just found out the muffler is rusting out! so I may live with it till next winter. Then maybe go with a true dual setup. I dont think i can put them before the cats....??? I havent taken alot of time to look under the car yet.

    Thank for all the input and advice!!

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    I like turtles GTP231's Avatar
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    If you're going true dual the cats are part of the y pipe so just drop it and sell it off to recoup some of the cost in your true duals. Seen some tuners run catted cars a lil richer than non catted cars so you could potentially see a slight gain in a tune. I wouldn't worry about it with the cost of a tune and just find someone to turn the codes off for now.
    If your muffler is rusting apart sounds more like a Chokemaster or a Spintech to me

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    Member devildogws6's Avatar
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    Yeah I can hear it its not a good sound too me lol, damn Midwest cars.

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    I like turtles GTP231's Avatar
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    Mid Atlantic and north we have the same problem

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    Quote Originally Posted by pajeff02 View Post
    OP: What kind of cats are on the car now? If you have a set of high flow aftermarket cats, you are not going to gain a whole bunch deleting them.
    I agree, what you will gain is a raspy sound like a truck around 3500rpms like I did when I went with resonators. I'm putting Magna Flow HF cats on as soon as I can.

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