still no check engine light and heres my theory... The Cats o2 sensor is put in one of the banks of the pipe and not reading all 4 so it doesnt show enough to make it go off. Or maybe the car just burns that clean.
2012 Audi Q7 TDI S Line ABTuning 391whp588wtq
01 Turbo Focus 300+ whp
2012 Focus 19" Niches, AEM CAI, F2 Race Header, 3" Borla Dual Exit, H&Rs, Eibach Sways 183whp157wtq