I bought my 4-2-4 Slip-on's a couple of months ago. It took me about 45 min to remove my stock pipes and install the new Nasty Boy's. They sound GREAT! Loud, but I can still hear my stero just fine. No rejetting required; however, when the pipes are cold I get a little popping when letting off the throttle, but that goes away within minutes or at least I can't hear it anymore (HA). Enjoy, I sure am. eddy1156