Aight a couple questions..im redoing my downpipe exhaust setup for meh turbo kit. First off, im running a wideband o2 and then the other one that plugs into the cat is stock. I want to get a downpipe made from the hot side of the turbo the where the stock cat is, then intstead of the cat get a test pipe. So my question is, I know ill need an 02 bung in the downpipe, but what about a testpipe, plugging the other o2 in there, wont in throw a CEL? Any recommendations? Also, should I buy all the flanges, bungs, etc and take it a shop so that all they have to do is the piping and welding? Or should I just have the shop do it all?