Thanks for all the info!
Jay - I honestly don't know for sure what scale is used over here, but suffice to say the shop that did the testing for me is one of only 3 shops in the whole state whose sound testing is recognised by our Department of Transport. They are required to have the meter calibrated frequently, and all testing is performed in a controlled environment. They did the test to the letter of the law. The owner is a friend of mine, so he wasn't just scouting for more work either
It was interesting that they mentioned that our local GM product with a V6 Buick derivative shows an 87dB reading, while the LS1 Chev motor in the same cars is right on 90dB (at around 3000rpm). They noted that one totally standard LS1 powered car that was 6 months and 10,000 miles old, gave a reading of 93dB..... If an untouched, stocko LS1 is over the limit, what chance in the world would any Cobra over here have?!?
Ant, the only Flowmaster cars with any power that I've heard are the Transam style racers (Sports Sedans). I must say that they "sound" louder than other mufflers to me. It seems like they have a much higher note, rather than a deep, booming note. What that translates to on a decibel meter is anyone's guess...
Dan, these guys only run their testing equipment up to 130dB, stating that anything over that is beyond the pain threshold. Once anything hits that level, they're out of there. Blowing all that sound out through the sidepipes at 6500rpm in top gear on the racetrack actually sounded quite nice with the helmet on, but if the revs go above 4000rpm on the street, it does give your ear a workout. More incentive not to do silly things on the street.....
In any case, what with the exhaust, three noisy fuel pumps, solid roller camshaft, cog driven supercharger with it's own internal straight-cut gear drive, and great volumes of air rushing past the bypass valve whilst in vacuum, I think the engine would have to seize solid before I'd hear anything untoward.... With the rear of my hoodsoop open (RS Camaro cowl-induction style), any mechanical noise just hits you straight in the face as if the windscreen wasn't even there.
http://www.clubcobra.com/photopost/d...122rollbar.jpg
Regarding the 102dB track limit. I wonder what 130dB at very close distance roughly equates to from 100ft away?
Jack, thanks for the link. A friend of mine has similar spiral mufflers in his 65 SS Impala. His 13:1 comp 509 cube streeter is insanely noisy at idle to the point that I cannot even hear the modified 460 running in my Falcon while sitting beside him at the lights. At the track however, his car at full throttle sounded only half as loud as my traditional mufflers. It's interesting that your car is quieter at idle with these. Maybe it's the combination of spirals and perforated tube that works best
