B-Pipe & Y-Pipe

[d3v0]

What's the difference between a b-pipe and a y-pipe, cause my car only has two O2 sensors and they're both on the exhaust manifolds, i don't have a O2 sensor on my cat so can someone tell me a little bit about my 99 max SE and provide some pictures as well?

[brianw]

y-pipe on the Maxima connects the two exhaust manifolds to the catalytic convertor, removing two of the precats in the process. Aftermarket b-pipes have a slightly larger diameter due to fewer crimps and kinks in the tubing, plus precat removal helps.

`95-98 + `99 fed-spec y-pipe.http://www.brian1.net/maxima/w...6.jpg

In the case of your 99SE, if it's a CA-spec car you have 3 precats and four o2 sensors, but since you say you only have 2...

B-pipe goes from the catalytic convertor to the muffler and has an o2 sensor bung in it, just after the catalytic convertor. The stock b-pipe has a kinked pipe for the o2 sensor in it (some call it the "s-pipe") as well as some restrictive crush bends, an aftermarket b-pipe will usually be larger in diameter as well to permit additional flow.

All 4th gens have at least 3 o2 sensors according to the FSM, although the o2 sensor behind the cat doesn't actually affect performance...

You can see the stock b-pipe here with one of the crimps in it...http://www.brian1.net/maxima/w...0.jpg