I've scoured the net trying to find any solid info on whether there would be a significant gain in HP/TQ going from a 2.5" X/H-pipe and exhaust to a 3" X/H-pipe and exhaust on our cars, but came up empty. Does anyone have any real world experience on the dyno or reliable information between the two? I recently watched an Engine Masters episode using an LS3 and they picked up +/- 20hp and 20tq going to the bigger exhaust. I'm in the process of trying to make my setup as efficient as possible, if there is 15whp/tq or more to be had, I may pull the trigger on a full offroad 3".