Changing to hi-flow cats only??
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I'm "Apache" a psycho dog
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From: N.J.
Changing to hi-flow cats only??
Has anyone changed only the cats to the Random Tech ones, without changing to headers, or cat back. Or maybe a combo of hi flow cats and cat back. I just cant believe the stock manifolds are restrictive enough to warrant the expensive of headers and mandatory change of the cats to. So i was just thinking of another combo underneath that might get some positive results with less expense. Thanks. 
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Originally Posted by Rob 99
Has anyone changed only the cats to the Random Tech ones, without changing to headers, or cat back. Or maybe a combo of hi flow cats and cat back. I just cant believe the stock manifolds are restrictive enough to warrant the expensive of headers and mandatory change of the cats to. So i was just thinking of another combo underneath that might get some positive results with less expense. Thanks.
Coupled w/ my GHL's, should wake up a few sleeping dogs!
From what I've heard, the stock manifold is fairly restrictive as are the cats. I've got 4 w/ the Vert. The Z06 only has 2 main cats, no pup cats.
In the meantime
and TTT
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You can pretty much expect 20-30hp increase with LT headers, and hi flow cats ...with only the cats???? Probably not much and not worth the effort and cost as the Random Tech cats are in the neighborhood of $500.00
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I'm "Apache" a psycho dog
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From: N.J.
WellAdjusted, sweetcharity, herein lies the problem for around $2300 for headers and cats gets me 20 to 30 HP, with no change out of the stock catback, if i changed that(catback) to, i may pick up a few more HP's costing me total around $3 grand or more.
Just trying to juggle the numbers and $$'s
Just trying to juggle the numbers and $$'s
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Haven't heard of anyone just changing the cats, but it probably would open up the exhaust flow a bit. A little gain may be had, but obviously the best route would be to do the headers too.
Thread Starter
I'm "Apache" a psycho dog
Joined: Jan 2001
Posts: 3,085
Likes: 31
From: N.J.
thanks JD, I was told i dont really need to change the catback part of the exhaust if i do headers and cats, the stock muffs wont really restrict that much anyway, so im lookin at about $2300 for headers, hi-flow cats and install, thats were im at right now.
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From: Between a rock and a hard place, S.E. PA
I've heard from several techs that the stock GM cats are not that restrictive. If you're looking for noticable gains, do it right and research changing the headers at the same time. You'll usually hear that long tubes pull better on the top end. Good luck.
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Joined: Jul 2003
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From: Bonita Springs Fl
Hi;
Going through the same thing. Talking to a tuner - tech and he advised to install TPIS headers with a H-pipe that installs just before the stock cats. A little welding. Than that will be stock till my Corsa Indys. He said that it will be a little louder and a little deeper. He also mentioned that the stock cats weren't that restrictive. And you save about $500. So you would end up having 2 H pipes. And you use all 4 sensors. No codes. Out the door price $1200. That includes everything. He has this system on his and it sounds good
Hopes this helps
Going through the same thing. Talking to a tuner - tech and he advised to install TPIS headers with a H-pipe that installs just before the stock cats. A little welding. Than that will be stock till my Corsa Indys. He said that it will be a little louder and a little deeper. He also mentioned that the stock cats weren't that restrictive. And you save about $500. So you would end up having 2 H pipes. And you use all 4 sensors. No codes. Out the door price $1200. That includes everything. He has this system on his and it sounds good
Hopes this helps
Last edited by rapid robert; Aug 4, 2004 at 11:45 AM.
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A friend just did shorties and random cats (cost avg. about the same as LT header packages). Picked up 20 RWHP. Some HP increase was from the loss of the pup cats, better flowing main cats.
Also a weight loss of 40 lbs. Compared to LT headers, he is smog legal (actually he would have to put stock center section back in if he failed visual).
Might be an option for CA folks.
Also a weight loss of 40 lbs. Compared to LT headers, he is smog legal (actually he would have to put stock center section back in if he failed visual).
Might be an option for CA folks.
