LT1 POWR

Does anybody have any experience with the Car Chemistry 2-disc or 3-disc header inserts, or the Dynatech Vortex cone? Supposedly they reduce exhaust Db. My new exhaust system might be a little too loud for my tastes and i was wondering if these would be worth the money. Does anybody know how much they reduce Db's? Anybody useing these? The Car Chemistry discs are $45.69 a piece for a 3" (race) 2-disc and $54.69 a piece for a 3" (street/strip) 3-disc. The Dynatech cones are $69.95 a piece. Would you need 2 of these, one for each header, or could you just run one after the y-pipe somwhere? I dont really have room in my exhaust for a bullet type muffler so this looks like the only option.