By going from a 6" 3" race muffler to a 2 1/2" exhaust system ( prob have a 12" of 3" pipe than reduced to 2 1/2" maybe 18-20" into just a "street car" muffler, no tail pipe) how much power will it kill? Car is currently going 10.9's. By installing a cut out in the 3" portion to open up later will the car perform the same as it did without the exhaust system (other than have the extra weight of the exhaust system)