ok, im thinking on buying a catback exhaust, so i decided to look for a used one, this one guy is selling his Greddy Evo 1 for 400$ with shipping. It has only been used for a year or so, i just wanted to know if this is a good deal on it? here is the pic below, he says that the stuff on it is not rust, just what happens over time to the pipes since there not stainless steel, is this correct? or am i gettin ripped off?



also what do you guys think about installing a catback? should i do it or get a pro to do it for me if its under like 50$?