So I had my new muffler(Vibrant Sleeper) welded onto my cat back a few days ago and basically I'm not happy with the levels cruising on the highway. It's only slightly better than the N1 without a silencer. And it will not pass NJ inspection in August. So I've been searching for a solution. First idea was a new resonator but price+install would be a up there and isn't even a sure fix. So I did a google search. And I found this CR4 - Thread: How to reduce exhaust noise.. It seems to be an engineering website. Seems pretty legit and has claimed a 13 decibel reduction. Basically its a small propeller/prop/fan. Think electric supercharger minus the electric. It doesn't interfere with exhaust gas flow much, if at all, but it interrupts the sound waves moving through the exhaust, thus decreasing the volume. Seems feasible to me. The article also mentions Supertrapp tunable exhausts which got me thinking... How about add more props? I figure it will increase interruption of the sound waves more thus reducing the volume more. Nothing crazy, something like 2 after the cat and 2 in the axle back. A set-up like l-l--l. The first part would be a flange/gasket between the sections of pipe with the second two being props, all connected through the center. So obviously I'm at least going to try this. But I want to test it. So where could I buy or hopefully rent a decibel reading device? And would it make sense to have the 2 props spin the same way, spin opposite ways, or be fixed? Comments, questions, other ideas, and critisms welcome.