It is my understanding that the 5th generation engine is very similar to the 4th generation engine....EXCEPT Nissan engineered a better air intake and exhaust system. Nissan claims the 5th generation vehicles have a 222 horsepower output....basically from the freed up intake and exhaust. Are any of the parts interchangeable with few mods?

I believe that the y-pipe from a 99-SEL is interchangable with the 00/01 y-pipes... can someone please confirm?

I think your right...all 99.5's, but I am not 100% sure.

Erik

or if you get the stillen pipe, it fits 95-01...for 95-98 vehicles, it has an additional pipe to connect to reach the other manifold....for the 99's cali spec to the 01's, that piece is not required, therefore making the stillen pipe 4th and 5th gen friendly

there are no 99.5's!!