Just a reminder to keep any warranty cards you might get when you get aftermarket parts. Purchased a magnaflow 4 catted x pipe, california legal 10/2010. Passed smog fine 11/2010 with pipe. Spent last weekend replacing the clutch trying to troubleshoot a knocking sound comming from around the trans area. Finally found the problem, something broke loose in the drivers side rear cat after only 200 miles, car has new oxygen sensors and plugs look good, (good air fuel ratio). Anyhow no luck getting a free replacement from Magnaflow with no warranty card. Tried contacting the place I bought the pipe from as I do still have the order # and email conformation but no recent responses. :nonono: