I've looked at http://www.greghome.com/Greg's%20Garage/1999%20Nissan%20Maxima%20SE/StillenB-Pipe.htm for the great write up on the Stillen and Courtesy B pipes. I'm going to be getting a new B pipe soon since I removed my entire exhaust today. The writeup here is concerned with a 1999 that DOES NOT have an O2 sensor behind the catalytic. On my 97, there IS a O2 sensor behind the car and it is NOT within the cat either. I hear the 95-96's have the O2 sensor IN the cat. On his site regarding the Courtesy piece, it appears as though this piece is already behind my OE cat to hold the O2 sensor. I would like to eliminate this piece cause it seems like it would restrict the flow some. From the findings on greg's page, I might just go with the Stillen unit as it looks like that one truly replaces everything from the cat back and has a home for the O2 sensor as well. I am not sure if the Stillen unit is stainless or not. I will be using the stock muffler. Any other experiences with a 97 SE regarding the Stillen vs Courtesy pipes?

 

You'll have no problems as long as you keep the stock cat. I have a 97 with the O2 sensor after the cat. I changed out my B-pipe with the Courtesy Pipe and it fit perfectly.