Straight-Pipe Questions

[GrahamDBraun]

Hi, anyone have any experience in a straight-piped Altima coupe? (Preferably 3.5)

I have a few questions:
- Does the car run rich afterwards (More specifically, rich enough to be an issue at all)?
- Does the CE Light come on afterwards?

Thanks, all
-Graham

[fyarf]

When you say straight piped, do you mean from the manifold back? or a y-pipe to straight back on out?

[GrahamDBraun]

Do you mean from the manifold back? or a y-pipe to straight back on out?

You'll have to forgive me, I'm a bit of a newb to car modding.

My understanding was that straight-piping originally referred to running a pipe straight from the Exhaust Manifold all the way back to the exhaust tips. But now, the term "straight-piping" more commonly refers to straight piping everything behind the Cat, including the Reso and Muffler(s).

The latter is what I meant to do to my car.

Am I mistaken?

Thanks!

[fyarf]

Both are valid, although true straight piping is from the manifold back. Our stock manifolds have cats in them that are regulated by the computer, so if replaced with pipes must be tuned out to avoid ECU warnings.

I put on a y-pipe and then straight pipe back to dual mufflers, and it works great for me ('08 V6). No resonator. Great sound, little to no drone.

[GrahamDBraun]

Our stock manifolds have cats in them that are regulated by the computer, so if replaced with pipes must be tuned out to avoid ECU warnings.

Thanks for your response!

I'm still a bit confused though. Do you mean to say that even if I take out just the Reso and Muffler, and don't touch the manifold or Cat(s) the car will still produce ECU errors?

Also, I've heard that it's possible to sort of "bypass" the muffler by loosening 2 bolts on a flange on the exhaust pipe. I believe the members name on here was Mehdi.

[fyarf]

We have 3 cats in the 3.5: one in each manifold (regulated) and a third in the exhaust line (unregulated). The racingline y-pipe deletes the third unregulated cat. This will not throw any errors, as the ECU doesn't "see" it. If you don't touch the headers, nothing else should throw an error unless you have a fuel/air ratio problem. Removing mufflers or a resonator shouldn't throw an error unless there is not enough backpressure or too much air for the fuel being supplied by the injectors.

Loosening the bolts on a flange in any exhaust line sounds like a bad idea. air leaks=lost back pressure and power, and probably crappy sound. Since our motors are mounted transversally (one manifold toward the grill and one toward the cabin) changing the headers is a pain and is very difficult. It is possible though, and you will have to tune the missing cats out, or put in faux cats or something. If you want to bypass the muffler, take it to an exhaust shop and get them to remove the muffler, and weld in piping to the tips.

I wouldn't endorse this, as sound will probably be obnoxious. But it's your car, do what makes you happy.