I know this topics been covered and I know a 2.5" is the best for nitrous/turbo applications. But what I'd like to know is, I plan on adding a Nitrous kit a 55hp kit by zex as soon as i get my intake, pulley, and cat-back installed. I know that 2-1/4" is the best for a n/a mods. Should I just get a 2.5" piping off the bat? i wanna know, just to see how much it'll affect my performance negatively/positively?

 

Well, for a car running any kind of power adder (nitrous/turbo/sc)yes a larger exhaust is a must but check this out. A very important factor overlooked is you current engine displacement. You're not going to want to put a 2.25" exhaust on a 1.3l motor. That's just too big eventhough those numbers (2.25") are what everyone talks about. I don't know too much about elantras specifically, but if you're running a 1.8l motor, i'd stick with the 2.25" piping even if your going to run nitrous. But even before that, your nitrous will probably turn you cat into a flamming hunk of metal (not literally but you know, figuratively speaking ) Stock cats get wasted easily when running any kind of power adder. I'd recommend replacing the cat w/ a hi-flow unit along with your 'cat-back'. I like carsound cats personally. Besides that, i hear OBD-II cats generally get clogged up over time pretty badly, so now you have 2 reasons to replace your cat!

Oh as far as a 2.5" exhaust being the exhaust of choice for turbo cars?... well, that depends on a lot of factors especially how much boost one is running. You're not going to run a 2.5" exhaust if your boosting like 25 psi. you're making some pretty insane pressure in your motor which equates into more hot expanding exhaust so sometimes you might think there never can be an exhaust big enough when boosting high!

[ August 23, 2002, 10:24 AM: Message edited by: Koreandude ]

 

My N/A Tiburon setup runs absolutely fine with an HVE 4-1 header, 2.5" exhaust pipe and 2.5" free flow cat. With a good header, you shouldn't lose your low end. What you may perceive as the low end being weak is usually because the top-end got SO much better and it "feels" unbalanced.

If you strap it to a dyno, you likely will not see a loss at all.

My turbo setup is going with a 3" pipe, minimum.

 

for a 55shot and full n/a mods you still want 2.25" diameter, but if your getting it crushbent piping, then you want a 2.5" piping. If your going turbo or high f/i then you want 2.5" mandrel.

the reson for this is that when you crush bend pipe, it lowers the diameter on the corners, so essentially making 2.5" piping 2.25" and 2.25" a little over 2". If you want a good madrel setup for 2.25" go for the mbrp exhaust or wait for a SR setup. Thats what i have now, and i'm fully N/A with future 75shot NOS.

The only bad effects from smaller diameter piping is loss of top end hp, but you keep lower end and have more torque. Unless your going to be doing a 75shot alot, your 55shot would be happy in a 2.25" piping (madrel) or 2.5" (crush).

hope that helps.