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      03-02-2010, 08:15 PM   #7
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Originally Posted by Andrew 912 View Post
I used Rear Section Dinan Exhaust previously and I would say about 20% louder than OEM Exhaust but I got Drone at 2100 - 2300 RPM. The drone was not as loud but quite bothering to my ear. I use Akraprovic Evolution Exhaust presently and I am very happy with the exhaust sound and no drone.
Originally Posted by Fen335i View Post
you are the first one I've heard of that experienced drone w/Dinan's exhaust. That is supposed to be the biggest the fact that it doesn't drone. Interesting...
Dinan had drone but Akra had no drone? Yeah, I call BS also. Dinan will have less drone than Akra for sure!. Most people would accept more drone than the Dinan exuast design because the get hung up on the single functioning tip. Or they go with the AA design with the external Helmholtz chamber. The Dinan exhaust was specifically designed to maximize flow while reducing low frequency drone.


"Or it was possible to get good flow and a low frequency drone with 4 tailpipe tips, but it was impossible to get both. We considered using an external Helmholtz chamber like some companies have done. But this added additional weight and cost and was deemed unacceptable. Analyzing other after-market manufacturer’s mufflers revealed that they had all made a compromise because of these problems. Either they had high backpressure from keeping the BMW design or very loud low frequency drone with straight through twin muffler designs or heavy expensive exhausts with straight through designs and external Helmholtz chambers."