I am not sure if this will interest anyone but I posted the note below in another thread a short while ago. My trackday has been and gone but interestingly my DB rating was 101db's at Snetterton last week which suggests that maybe the cheap db meter I mention below is a little more accurate than I would have given it credit for, I appreciate noise will alter with temperatue etc. but maybe some people might want to consider a cheap meter just to get a ball park reading or to check the level after repacking. "I just bought myself a sound meter from ebay for £10.00, I have no idea how accurate it really is but it recorded 103.8db for my 748R without baffles and 101.4db with them in. I compared that to my 748SPS at 102.8 without baffles. Both have carbon Termis. It is claimed that the meter is accurate to +\- 1.5db. It might be worth a thought as to buying one as it looks like it will give you ball park figures. I also suspect it fractionally over records. I repacked my 748R Termis with Acousata Fil so it is interesting to compare the difference between all the readings, so clearly with my trackday coming up at the end of the month I am going to have to go with DB killers."
You can get free Db apps for your iphone. Not sure how accurate they are but they can't be too far off I wouldn't have thought.
I used to have to do sound level checks on power station equipment and would think that the accuracy of these things will be around 5% or so. Noise meters are notoriously inaccurate and even the professional bits of kit have to be full calibration checked before testing then spot checked immediately before and after testing to prove they haven't drifted. The positioning, background noise and reflective surfaces close by can also make a significant impact on the reading obtained. I hated having to do it as it all seemed to so hit and miss. At a trackday with some untrained marshal picking up a probably uncalibrated meter and pointing it a bikes general direction probably doesn't prove anything hence the reason people with the same bikes and pipes often have big differences in the values recorded. But its a bit like getting pulled you simply can't argue they are the law and the rules (no matter how stupid) are the rules. Just my opinion, from a bit of experience, sorry if its a bit negative John
