High flow cats/ race pipe
Team Owner
Joined: Sep 2003
Posts: 43,084
Likes: 33
From: Raleigh / Rolesville NC
High Flow cats are better then stock cats. If you have no cats you will get a ponie or two more.
The advantage is the exhuast will not smell as bad with the high flow cats vs without cats at all
The advantage is the exhuast will not smell as bad with the high flow cats vs without cats at all
Safety Car
Joined: May 2000
Posts: 4,821
Likes: 347
From: Albuquerque NM
Originally Posted by AVB
Unless you are turbo'd it's not worth being catless.. high-flows are always worth it.
I gained 15 RWHP simply by replacing my 2 cat mid pipes with a 3" no cat set of mids with X pipe. Show me that kind of gain using high flows.
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Thread Starter
Intermediate
Joined: Aug 2006
Posts: 40
Likes: 0
Interesting responses. I would like to stay leagal, but since I put less than 5000 miles on a year i'm exempt from emmissions. I don't want that nasty exhaust smell that I had from my cam/heads no cat TA. IF it is only a few ponys I'll go cats. IF it will be 15 or more I'll have to really think it over.
Oooooh yea I plan to go with a super charger in the future.
Oooooh yea I plan to go with a super charger in the future.
Race Director
Joined: Jun 2004
Posts: 19,459
Likes: 48
From: Schaumburg IL
CI 7-8-9-11 Veteran
St. Jude Donor '06-'10, '13
I kept hi-flow cats on because I don't want the smell, and even with the Hi-flo cats every once in a while I get a slight smell.
In terms of HP gain on hi-flow cats vs no cats.... I wouldn't believe in a difference or any gains unless I saw an apples to apples comparsion... s 2 cars with same mods and tune, one cats one no cats, otherwise there are too many factors to take into account to really say if there is a gain in HP.
tune, mods, miles on the car, type of headers, type of dyno etc...
In terms of HP gain on hi-flow cats vs no cats.... I wouldn't believe in a difference or any gains unless I saw an apples to apples comparsion... s 2 cars with same mods and tune, one cats one no cats, otherwise there are too many factors to take into account to really say if there is a gain in HP.
tune, mods, miles on the car, type of headers, type of dyno etc...
Thread Starter
Intermediate
Joined: Aug 2006
Posts: 40
Likes: 0
Originally Posted by Nulltime
Wait a sec...so if its 5k and under miles per year you don't have to pass emmisions?!
Safety Car
Joined: May 2000
Posts: 4,821
Likes: 347
From: Albuquerque NM
Z06sicks: In my mind, the only reason to go high flows is to reduce the smell and loise level.
I know my response caused some raised eyebrows, but it's true. To be federal emissions legal, the factory cats must be used, in the factory position. Period. The only part of the exhaust that may be modified is the "Cat Back" portion, or something that doesn't replace or move the factory cats. Hence shorties (CARB cetrified) are legal, long tubes are not.
So, if it's illegal either way, why high flows? Do a search, you'll find many people who still get the CEL for improper cat operation when using high flows, and still get the smell. Either symptom indicates the high flow is not working. I have high flows on my truck, and have the trouble codes set for cats not working.
I helped gut the cats on a friend's Vette, he gained 6 rwhp. I replaced the cats/midpipes on my Vette with smooth pipes, and gained 15 rwhp.
So, ya wanna stay legal? Don't mess with the factory cats.
Ya wanna feel good but still be illegal, go high flows.
Ya wanna make horespower, delete the cats.
I know my response caused some raised eyebrows, but it's true. To be federal emissions legal, the factory cats must be used, in the factory position. Period. The only part of the exhaust that may be modified is the "Cat Back" portion, or something that doesn't replace or move the factory cats. Hence shorties (CARB cetrified) are legal, long tubes are not.
So, if it's illegal either way, why high flows? Do a search, you'll find many people who still get the CEL for improper cat operation when using high flows, and still get the smell. Either symptom indicates the high flow is not working. I have high flows on my truck, and have the trouble codes set for cats not working.
I helped gut the cats on a friend's Vette, he gained 6 rwhp. I replaced the cats/midpipes on my Vette with smooth pipes, and gained 15 rwhp.
So, ya wanna stay legal? Don't mess with the factory cats.
Ya wanna feel good but still be illegal, go high flows.
Ya wanna make horespower, delete the cats.
Safety Car
Joined: Jul 2001
Posts: 4,661
Likes: 67
From: Ocean Springs MS
Originally Posted by mark896
****! Now I'm wondering if I should even buy cats. Maybe just an x-pipe now..
Team Owner
Joined: Dec 2001
Posts: 48,767
Likes: 50
St. Jude Donor '03, '17
Senior Member
Cruise-In V Veteran
Or you can live in Olive Branch like me and not have to worry...I just am tired of the smell. Does anyone know the best place to buy...I don't want to get screwed