I have .326 exhaust on my spec v now, and I'm putting a borla muffler on with a .250 inlet... will I lose any ponies from that?

check the inside diameter ID of the pipe. i'm sure it is not .326. that might be the walll thickness, or thickeness of the tubing material.

check your numbers again. most exhausts on Nissan Sentras are about 1 1/2" or 1 3/4". that is stock. aftermarket performance exhausts w0uld be larger.

Sorry, it's 2.36 ID.

2.36 < 2.5

2.36 < 2.5

Muffler ID = 2.25
Pipe ID= 2.36

i say get an adapter for it. with .09" difference, you will probably not notice anything.

i wouldnt worry about it. i wouldnt do it myself but if you have the parts... when it comes to the muffler you can never have too big. even most cars can run as big an exhaust as you want from the cat back without any penalty(besides noise)

I have an apexi WS2 set up, now. Super quiet.

you might get a little bit of tourque from a slight bit more backpressure but shouldnt notice it