exhaust for 90 pathfinder

I am using a flowmaster 50 series muffler with 2.25'' pipe. I have been quite satisfied with this and I noticed (slightly) better power than stock.

so you put in headers? where did you start the 2.25" pipe after the cat? how does it sound i want it deep but not so loud

I am still running the stock manifold... poor college student and all, planning on headers at some future date.... I started the 2.25 after the cat, it seems to be (at least to me) decent sound. If you don't want really loud I would avoid the flowmaster 40 series, I have a friend with that muffler on a VG30-E hard body and it is quite loud, especially on the highway. The 50 is quieter, although it is by no means quiet. Another option would be a dynomax or magnaflow type muffler, these are a little quieter (than a 40 series at least). The best advice I can give you is to find someone with a rig that you think sounds good and find out what they are running, that is how i finally decided on my setup.