Hi flow cats
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
I would say very little--3-5 HP--AND you have to be sure that the ones you chosse will indeed pass emissions--here in Calif--most Hi-flow cats won't and the only ones that will are the Random Tech's and they are very pricey-I made the mistake of intalling some of the bullet style SS metal substrate hi-flows--They claimed to be Cailf legal--Were only $70 each---BUT had to remove them as they weren't even close as the Nox was way over-- Put the stockers back on-----IMO-not worth the trouble--A good X-pipe is better--
Drifting
Joined: Apr 2000
Posts: 1,390
Likes: 36
From: INDIANA
Hi flow cats really are only worth it if you have long tube headers and need them cause the factory ones won't fit. There is not enough gain otherwise. I can smell that my hi-flows don't work like factory, when cold anyway.
