mmm since my car failed smog and im think and wanting to barrow someone stock exhuast system... i wonder how long does the average stock exhaust system including the cats usually last?

 

depends on how your car runs.. they last a few years.. if your car runs super rich it could kill the cats etc.. ive had to replace teh cat within 2 years of replacement on my old 240sx once because it just ran horrible and would fail smogs

 

Mines still going strong and its a stock 91 cat with 80k miles on it.