Anybody know what the best mandrel bent exhaust pipe diameter is for a B15 Sentra with an SR20DE? Already done the muffler (no gain...big surprise huh?...lol) now its time for the pipe.

2 1/4 is the biggest you would want to go on a N/A car.

Thanks, I have heard either 2" or 2 1/4" but definitly nothing over that. Is there much difference between a 2" or 2 1/4"?

Just remember that most shops go by O.D. not I.D. The actual size of the pipe will be smaller than what you thought, or wanted. It all depends on the wall thickness of the pipe being used. I would go with 2 1/4" O.D. tubing, so you would end up with a 2"- 2 1/8" exhaust.

Cool, thanks!

No problem. Let us know how it goes.:)

If your stock piping isn't about to fall apart, like mine did, I would just leave it alone.
My friend went with 2" and I went with 2 1/4 " on our identically modded Classic's.
I have a very slight edge on him @ high RPM's but he has more down low than me.

2 1/2" has been known to work. Both Shell's and, I think, Shaggy's car made respectable gains with 2 1/2" systems. One was the Courtesy catback and the other was a DIY, IIRC. Both have dyno charts.

If you don't plan on getting cams, then 2"- 2 1/4" will be just fine.

Just some more data points.

How does that Ravin(sp?) sound?

http://users3.ev1.net/~bahearn/exhaust.htm

Here are pictures of the Courtesy exhaust before I installed it on my car.

As for "best" diameter, there is no firm conclusion. Tests made by one of the muscle car mags 10 or more years ago found they couldn't go too large; bigger pipes kept giving more power. They tried up to 3" ID before calling it quits. I suspect that the primary issue for us is availability and installation space.

Originally posted by peter96
2 1/2" has been known to work. Both Shell's and, I think, Shaggy's car made respectable gains with 2 1/2" systems. One was the Courtesy catback and the other was a DIY, IIRC. Both have dyno charts.

If you don't plan on getting cams, then 2"- 2 1/4" will be just fine.

Just some more data points.

How does that Ravin(sp?) sound?
Sounds really good.
Funny though, the Midas guy that installed it couldn't believe I wanted it on a Sentra. The other guys there were saying its intended for V-8 exhaust, but I know that other Sentra owners have installed them so I figured go ahead.
They were telling me it was going to be really loud and I might not like it and wouldn't I rather have one of their regular setups. I said no, put it on and when they started the car it really wasn't all that loud and sounded pretty cool, they were impressed.
I put it on, not figuring on much of a gain til I do the pipe, but I liked the sound (someone posed a sound clip somewhere else, don't remember where) and wanted to get rid of the two stage muffler.