Quiet mufflers

good question, my car has flowmaster 40s which are not quiet mufflers, it was real loud.i cut them apart and welded another 40 series to the original ones.thought it would be alot quieter,it's quieter but not by much.so still looking for quiet mufflers that won't kill performance!some of the aftermarket mufflers we tested slowed the car 5 or 6 tenths!