now, i have just been out on my bike, got home, thought i would give it a spit and polish. don't ask me why but i ran my hand under the exhaust while it was running and felt it blowing. i looked under and have found a hole. it's about 2 inches from the join (weld), on the larger part of the exhaust (the part that has the baffles in). sorry, i don't know what else to call it. the hole is perfectly round, no signs of rust or other damage and is about 2mm in size. it appears to have been put there deliberately. any ideas guys.