This is on a GSR? Do you have an aftermarket ecu? It's great that you want to get rid of that POS manifold, however, if you have a stock ecu, and that skunk2 doesn't have the 2nd butterfly, URFUCT. Wait until you have a chipped ecu that doesnt want to open the 2nd butter fly. Your car will not run happily when that 2nd butterfly opens. Other then that issue, the skunk2 manifolds are PROVEN to make 8-18whp difference. You will be happy. Don't listen to rangecrx.