Huh, cause if a code still gets thrown from the post-cat O2 sensor, doesn't that affect how the computer calculates the air/fuel ratio? And for inspection's sake, there must be a way that people do this in order to keep that SES light from comin on and raisin questions. Reason I'm askin so much about this is I'm trying to get a mental plan/layout for my exhaust upgrade, and if I can just take the cat outta the picture I'd be just happy. Thanx for any help