One word, SpinTech! Oval is the answer. Every lowered pro touring car should use oval pipe for ground clearance, and flow. You can get a oval X pipe in 3" that will only be less then 2" thick, more ground clearance, more flow. Get 3" oval inlet, 2 1/2" round outlet mufflers, and use 2 1/2" tailpipes. Quite, husky sounding, and no power loss.
We can hook you up with SpinTech stuff at GPSuperStore.com
www.spintechmufflers.com