Most of these "gp" style pipes on ebay are actually exhaust tips you could buy at autozone, not meant to "baffle" sound but rather to look good (on a car). Many times using an "exhaust" like this will cost you horsepower because of volumetric loss. Much like too little back pressure, too short of an exhaust is a bad thing as well. My suggestion would be to cut the pipe you have or look for other replacements.