donington park is a feck for it, the db sensor in on the start/finish, stay to the right of the track before moving to the left before redgate.
when i was there last in the vx220, my friend popped along in his dc5, he last 3 laps before being black flagged. saying that, his exhaust is stupidly loud. after being measured his car was louder than matt neils dc5.
just be careful, as if you got slowly past start/finish and gun it around the rest of the track they will still get you and do a static test.
streaming vtecs with full system are easily over 98db.