Novice Exhaust Question "Y" Pipe

**89LX** · 06-16-2006, 02:20 PM

Yip I read the threads and will risk the butt chewing and ask a question. I have a Hooker CB Aerochamber on my 2000 Z28. The installer said I need a "Y" Pipe to free-up more flow. I see the term "Off Road" Y Pipes by SLP and others. Why are they called "Off Road" (something illegal for street)? I see the sales sites don't mention anything about emissions so assume this portion of the system is unaffected in that respect. I can easily see why a round pipe will flow better than a flat one. I would like to keep my sensors in place and stock headers for now. Thanks for the help.
2000 Z28
M6
SLP Lid
Smooth Bellows
Hooker Aerchamber CB

**Schweet97Z** · 06-16-2006, 05:50 PM

yes ory pipes are illegal. they dont contain cats. in my opinion there not worth the money when used with manifolds. save ur money for when u get headers..or do another mod.

**89LX** · 06-17-2006, 04:45 AM

SLP Ad says "SLP's Y-pipe assembly is available for 2000-2002 Camaro/Firebird with V8 engines. Manufactured from 2-1/2" O.D., 409 SS tubing, it is mandrel bent for smooth, clean bends with superior flow characteristics. This Y-pipe assembly is designed to replace the "flat" factory pipe (behind the stock catalytic converters) and bolt to your stock exhaust manifolds." So am I to believe my cats are up stream and not affected? Maybe my first post wasn't very clear. They (SLP) further state up to 10 WHP gains possible. What do you think? Thanks

**sunsetorangess** · 06-17-2006, 06:54 AM

Well it says it bolts too your manifolds so im guessin it eliminates your cats. Gonna have to call slp for more info. If your just tryin to replace the y and leave the cats then save your money. You wont feel any difference and if anything you will just create a headache from replacing factory y. Just my op. thou
J

**Aegnor** · 06-19-2006, 12:55 PM

No, the SLP Y was designed to go on after the stock cats and manifolds. The only difference between it and the stock Y is that the stock Y is flattened under the drivers side for clearance, but some flow tests (and not a few lengthy discussions on fluidic mechanics) about three years ago determined that you really don't gain anything with it. The GM engineers did a good job with the design of the pipe and it flows as good as you could want on stock manifolds and cats. All using the SLP pipe (or any other Y that is "legal") does is loose you an inch or two of ground clearance and a few hundred dollars.

That being said, technically any other header/y-pipe combo besides shorties is federally illegal, since federal regulations state that it's illegal to move the catalytic converter any farther from the cylinder head than it was when it left the factory.

However, if you're registered in NC, most of the places just do a curosory visual to see if you have cats. If one wants to be a dick and fail you for having long or mid-length headers and a catted Y, go to someone who doesn't. As long as the computer on OBD-II (post 1996) cars say your emissions are okay, you're good. Most will not, however, pass you if you go with an ORY (no cats at all).