Had a Magnaflow cat back system installed - tried to do it myself since all the reviews I read said it was a simple swap. Yeah, not so much. Unless you have welding or cutting equipment in your garage there is no chance of getting the stock exhaust off the vehicle. Nissan likes to clamp the pipes so tightly that it crimps them together. After 4 hours of frustrating futility I ended up paying a muffler shop $80 to install the Magnaflow.
Long story short, it sounds great (no fart can Honda sound)and my X breathes a lot better. Plus, I now have a new muffler which, after almost 10 years, needed replacing anyways.