Hey everyone, bought a 2005 TT Quattro, 3.2 S line, after owning it for 2 months I got a CEL, a generic scan tool said p0420 and p0430, so now for my question, can I replace with say a OEM aftermarket such as Borla or magnaflow etc.? I've heard aftermarket parts aren't well tolerated by audi's? I was going to go direct fit oem style. Any advice would be greatly appreciated, thanks