My debate is I have a Grimmspeed up pipe which I purchased THEN realized the OE up pipe is already catless. After reading numerous forums it seems there is no considerable gain in performance going from OE catless to aftermarket catless. I was hoping a few of you have experienced this situation and could share your findings. My main issue is: why would I spend all this money on high quality parts that don't make my car perform any better and aren't working towards better aesthetics, seems stupid. Thanks in advance.