I have a 21 sgs. I was thinking about having the se highflow exhaust installed . I was thinking that would give better sound , performance and keep my warranty intact. I would upgrade the air cleaner with se ventilator extreme along with se tuner and auto tuner if they have available. Then once warranty runs out do the complete stage 2 with good quality aftermarket parts. My real question is are the se head pipes serviceable with just a better muffler upgrade.