First of all, I live in California.. And I'm not sure if the laws are different else where, but we are not allowed to change our cat and put an aftermarket cat on. So for me that means stock cat stays. I know, I know, I could always just take the chance of putting a highflow cat, but if I get pulled over and get caught with that aftermarket cat, there goes my car on the flat bed. Not really willing to take that chance.

Anyways, I've been asking around, and I've been getting way to many different answers. Okay so catbacks are rated to increase HP, but if coming from a stock cat, wouldn't the same volume of air come out of the cat regardless, and thus not increase HP? I'm just trying to use logic, because I dont really know how that would work. Because the Agency Power catback bottlenecks down to the stock cat for easy bolt on, but it rates a 12 HP gain.. How does that work?

What is the diameter of the stock cat?

 

Morning BUMP!

 

Help?

 

Because the exhaust is larger in diameter after the cat there is less resistance. The resistance is related to the diameter of the pipe times the distance that diameter runs, so a catback would gain power.

On a side note, you should just do a cutout then like QTP, and keep the OEM cat and catback.

 

Is that right? There are not any CARB approved cat's that you could use? Seems un-american.

 

In California, the you can't replace the stock cat with anything other than the same unit... and that's only if the factory one breaks or if you have more than a certain amount of miles.

 

thank god i live in Chicago, they check for nothing, just check for codes while on a dyno to simulate regular driving.

 

Here you go.

http://www.worksevo.com/store/produc...roducts_id=244

 

OMG thats awesome! Thanks so much!

 

I think you'll benefit from the cat-back