Did drive it there last time but I did give it some abuse when I went to warm it up the 3rd time lol. He reckons they calibrated all the time? Can't see why it would have been a
problem because it's a Monday near by neighbours would have been in work and even with me going out +3dB's it wouldn't have made it no where near as loud as Performance Car Action Day!
Don't tell me the rally cars at Rally Day were below 100dB's!!!?
few things:
combe are monitored for noise by the council, and are mandated to keep it below the levels, on all bar the few "approved loud days", of which track days are'nt
their operating licence is at risk if they dont keep noise down, all thanks to neighbors who complained when moving next to the circuit a few years ago. (they nearly closed, and did loose F3 from the circuit as a consequence)
3db(A) is in fact a doubling of sound pressure as its a log scale. 103db(A) is too loud for sure..
The exhaust changes and gets louder with use.. as the packing expires and gets blown out. my
ibiza starts with fresh rear silencer packing at 89db(A) and after a few races approaches the 105db(A), at which point I repack the silencer and it returns back down again. Exhaust when used on track get louder as they wear and heat/blow out their packing.
Atmospherics also play a part... cold damp denser air vs hot warm air, effects noise, but I suspect your issue is your silencer packing, and you have been too marginal on passing previously and just tipped the wrong side.
I converted by rear silencer to repackable by cutting a rectangular hole in it, and making a plate to cover it which overlapped by 10-15mm, and riveted the section back down once repacked. Merlin sell packing pillows for about £12-£15 I think.
good luck