Hey guys, I have a 1999 VT Calais with a HSV 195 engine that came as a factory custom, i took it into the local tyre and exhaust shop and they recommended to put on a twin 2.5in system with straight through mufflers and high flow cats, i said i wanted it to be deep note with a good bark, but im not happy with it it seems to have some sort of whipping wisp at higher rpms but at lower rpms it drones like HELL, i heard that the same setup but leading into a single 3" from the diff back is a good note all round. Any suggestions, Thanks