Won't sound like shit. I don't sit behind my car and smell it so I can't speak to that.

supposedly a 1K Ohm resistor inline with the black wires will trick the ECU. Not positive this will work on a secondary O2 but it does on a primary.

You won't notice any real performance with a test pipe over a hiighflow cat. why 2.25? 2.5 would be better no?