Spin Tech mufflers

I got a set of 3 inch older models. Got them cheap at a swap meet and ran them behind a 451 with about 4 feet of exhaust. Sounds deep and solid, but doesnt have the resonance of flowmasters that gets on everyones nerves after about 20 miles. Mine weigh about 5 lbs a piece and are about as big as a boot box. You cant get that sound from lightweight turbos.