Depends how loud it actually is to whether or not they will let it on track at Snetterton, ...looking at around 102-105dB maximum with a drive by 92dB max.
You could always try one of those free Apps you can get or an actual dB meter to see how loud the car actually is. You might be surprised although with the tubular long headers which it sounds like you have it's going to be close on the limit that's for sure.