I just installed SD headers on my 98 grand prix and I got tell ya after all the tweakin to get them to fit right holy S**t what a difference. My only prob now is the car has mad vibrations while in reverse. Anyone else experience this? I've swaybar clearence and o2 clearence but how could that crappy o2 sensor vibrate against the firewall lil that and still be fine? Solutions anyone before I start tearing this thing back down to figure out its my only beef with this install.