NYNick

Has anyone evaluated the decibel/noise level of the various muffler brands and models of choice for these cars? A side by side comparison would be ideal. It's difficult to judge based on youtube videos, especially when people are running different headers etc.
I know what I like, and what I think is too loud, but this is my opinion and subjective at best. An objective comparison based on stock setup would be ideal.

Tuners?

Nick

Steve Weiner-Rennsport Systems

Hi Nick,

The main reason why such comparisons are not very accurate nor useful is due to the effect on sound by an engine's configuration.

Displacement, compression ratio, header design, and camshaft profile are just a few variables that affect what you hear from the exhaust. Its virtually impossible to make apples-to-apples comparisons, even using the same muffler combo,....

I have a professional sound level meter since our local tracks are tough, but my measurements are only valid for a particular muffler on a specific engine.

Lastly, perceived sound pressure levels are completely subjective which makes this exercise quite difficult. My best advice is to listen for yourself to determine what you like and can tolerate for long periods of time. For street cars, "less is more" remains my mantra,...

NYNick

Thanks Steve.
Of course I understand that different configs produce different db levels.
I was just wondering that with so many stock 3.0's and 3.2's out there, if anyone had done any measuring of just the muffled effect.
I guess it's back to 'seat of the pants/ears!'

And BTW, I agree with your mantra...

Thanks

Nick

Reiver

The quietest muffler I've had on my SC is the present Dansk 2 in 1 out. It gives great low/mid range torque too.
It is quieter than the stock Bischof and much quieter then the M&K.
I liked the M&K sound but not the loss of mid range torque that came with that....there is the trade off.
Lots of 'throaty' aggressive sounding (free flowing) mufflers sound great but lose mid range torque for more flow at the top end.
Depends where you spend most of your rpm time...I opt for the lower end grunt.

KILRWAIL

The following “evidence” should be considered anecdotal at best, for all the reasons that Steve stated above. But it may be of some interest. When I bought my ’77 911S in 2006, it had a ’79 3.0 litre engine that was basically stock, with CIS and SSI’s. The muffler on it was a B&B (Billy Boat) stainless 2 in/one out that sounded awesome to me.

Calabogie Motorsports Park opened October 1, 2006 and everyone had to have a sound check for the initial parade laps because of commitments the track had made to the community regarding noise controls being in place. At the time they didn’t know much about sound level testing, so they asked every driver to blip the throttle to red line while the tester stood about 20 ft behind the car. My car registered 110 dB and was not allowed on track – I believe they were looking for something in the low nineties. Oddly enough, I have sat at a red light in traffic beside a police car and he didn’t even look at me. Over the next year I tried several devices to quiet it down, but they were all cumbersome and probably robbed performance.

At the end of 2007 I had the engine rebuilt, enlarging it to 3.2 litres, but still with CIS. I was able to get through the sound checks at Calabogie with the B&B because they changed the testing procedure to reduce the rpm’s to 2/3 of red line. But a year or two later they started measuring on-track sound levels at Le Circuit Mont Tremblant and they became more restrictive than Calabogie. Around that time I switched to PMO carburetors and more aggressive cams, adding a Bursch muffler to improve performance and lower the sound level – still using SSI’s. However, I was black-flagged at Tremblant for recording 92.1 dB at 6000 rpm coming out of Turn 6, measured at about 100 ft (they were looking for a max of 92.0). Short-shifting in the vicinity of the sound tester solved that problem, but that wasn’t much fun. Of course I never had a problem at any other track in the northeast. That muffler now measures about 90 dB at 4000 rpm and 95 dB at 5000, while stationary in the paddock at Calabogie, which is acceptable there.

To solve the problem at Mont Tremblant, I bought a used 1970’s stock muffler, which I use only for that track. It’s never been tested at rest in a paddock, but it’s quiet enough to get by the noise police at Tremblant at WOT. Fortunately it’s easy to change one for other, so now it’s part of my regular prep for Tremblant. I occasionally use the B&B just for entertainment on the streets and country roads, just because. Although there’s likely a performance difference among the three mufflers, I’ve never noticed it to be significant. Compared to all the GT3’s and Turbos that I typically run with, the car is always pretty slow!

NYNick

Thanks Killerwhale. Loved your write up...
BTW, headed to "The Cottage" in 10 days...up on the Georgian Bay!