In Proddie racing most silencers were modified the one on my Venom was raised about four inches and the side champhered for clearance on full lean and the standard baffle which was modified so that it would drop into the silencer body after a good blip of the throttle this got it past scrutineer ING the other thing was a gutted battery case with a dry cell so the lights would work and the ammeter would move but the dynamo was disconnected so saved on weight and engine.. Daft thing though I never had Ally rims that were an option...
Rules were the bike had to be standard as anybody could buy only factory extras allowed centre and side stands removed. Racing tyres allowed lights must work but be taped up seat could be altered. Foot rests if an option. A flyscreen was allowed. No advertising.. Engine internals had to be standard but could be lightened and polished Carb standard.