Quieting down a loud PV muffler?

[Grant Eaton]

I've had my 2nd generation PV muffler for about 1 month now. It has 2,000 miles on it, and while it has mellowed considerably, it is still too loud inside the cabin, even with the Dynamat I have on the roof and inside plastic panels! The worst noise is the chassis-rattling drone at around 30 MPH (1,500 - 1,800 rpm). It sounds just like blowing into a beer bottle, only you're stuck inside the bottle!

I really like extra acceleration kick and want to keep this muffler. So, what can I do to quiet it down without robbing too much power? There's a lot of information on the Web, but not much for people trying to quiet down a performance muffler.

Bsically I'm considering the following options:

1. Dual exhaust. I'm getting this for looks-improvement only. Perhaps it will have the side-benefit of channeling the sound out both sides of the rearend, and make things sound more balanced as a result.

2. Resonated tips. Some people claim they absorb noise, others swear they make the exhaust drone louder and more annoying. What's the truth?

3. A noise-control tip. I've only been able to locate one example on the Web. At $80, it's not cheap and it doesn't come with any scientific evidence for decibel control. However, the idea of using perforations or baffles to help absorb sound energy makes sense.


4. An additional noise control muffler (aka inline resonator). Hopefully this won't rob much performance. Perhaps it would be possible to insert one of these inline between the engine and the PV. Or even after the PV.



5. Noise control pipe baffle. This is susposed to be inserted between the PV and the engine. It's designed to reflect sound energy back into the pipe while maintaining air flow.



Any advice on how to get rid of the "beer-bottle effect" and quiet down the overall exhaust would be helpful. Thanks.