Today I was looking through Ebay(nothing much else to do when you're snowbound)and found a guy who was selling a "Zigen" 2 1/4" inlet muffler with a removable sliencer with it. The silencer was held in place by a set of four locking allen-head bolts. It supposedly cut down on the noise quite a bit. Has anyone heard one of these mufflers on any type of car? Is there anything to be gained by just having this muffler welded on istead of having a cat-back system, or will I lose some bottom-end torque?