Originally Posted by alpine92m3
Thanks a lot! That really helps .! I was thinking about replacing them
With just straight pipe.. Do you think that would change the sound at all ? or should I stick with just gutting the cats instead? P.s I'm having an exhaust shop do this . Thanks again !
It will make no difference if you go strait pipe or gut the secondary cats. Actually you might get better performance out of strait pipes because there will be less turbulence from the gutted cat, but the difference would probably only be seen if you flow tested the x-pipe (no noticeable real hp/tq increase). So it up to you, but if you have a visual inspection in your area for emissions you will want to gut the secondary cat as it will look stock and there Will be no red flags as to what was modded.