JHarrison92

whats the difference?.......... bore diameter?......reliability?

gman73

Unless it's an O/R H, there will be no noticeable difference.

Projectquick

Did you really just ask about the reliablity of an exhaust part? gman, if you get a crossover pipe with high flow cats you will certainly notice a difference, in fact most of the aftermarket crossovers come with either no cats, or high flow ones.

gman73

I know that hi-flow cats will change the sound, I have hi-flows on my car, but just bolting an aftermarket H-pipe to the stock cats wont make that much of difference.

Projectquick

The cats are on the h-pipe, so if you change the pipe, you have to change the cats. High flow cats will do more than change the sound, they will flow a lot better, and make more power than the stock ones.

gman73

Do they even make an H-pipe that will bolt to the stock cats? I know you can bolt some X-pipes and prochambers to the stock cats. Of course you have to do some cutting. As far as HP gains, I bet hi-flows will only add about 1-2. With stock cats and h-pipe I dynoed 299RWHP/309RWTQ. With an O/R prochamber I dynoed 302/305.

danGT06

I'm confused... what do you mean an H-pipe that will bolt on to the stock cats? The car comes with an H-pipe.

gman73

I know the it comes with an H-pipe, but I wasn't sure if the o/p was comparing the stock H and cats to aftermarket H that would bolt to the stock cats-even if that's possible.

sweetlou69

mac prochamber is an H-pipe that uses the stock cats, u can also get the prochamber without cats

Projectquick

So the O/R pipe got you 3 hp, but the high flows will only get 1 or 2? I say the high flows are a better option because if your car has to go through any type of emission inspection you don't have anything to worry about. Then again, I wanted my car LOUD, so I said F*#k it.