I would agree with every thing that Utopia has said and you would do well to take his advice and check the belts asap.
Regarding an exhaust leak; while they do let exhaust out, any leaks near the manifold seem to let air in also and it's this that makes all the pops and crackles.
I think the noise could be consistent with a blowing head joint (no gasket afaik) and possible snapped stud!
Years ago the head gasket blew on one of my Ajays and I suppose you could describe the noise as a clapping sound. It was very loud and present at all revs, I guess the volume would depend on the size of the blow and the throttle setting.
I have also had spark plugs blow out following a weird "clapping" sort of sound (I assumed tampering in that case. It was a Yamaha YDS7)
A friend of mine once had a mysterious top end tapping sound on his Fire Blade, that many of us listened to and failed to diagnose.. He had it stripped at a shop and they discovered loose spark plugs (after the strip!).
Noughties triumph triples also suffer from a bizarre squeaking sound caused by slightly loose exhaust manifolds.. If you imagine the sound you make blowing through a blade of grass trapped between your thumbs, it's like that.
So in general I think that air or gas escaping through a thin gap under pressure could well be the culprit, but please do check those belts first..
