Petrol sounding like diesel? and clutch...

this is more of a curiosity thing than anything, but my 1.6L petrol motor with a 32/36 weber is sounding like a diesel at anything more than half throttle. what causes this??? it still goes OK no spluttering and revs smoothly to redline without any problems.....

like i said, it mostly for my curiosity than anything. :)

also, probably more important. my clutch is almost gone. need a new one. how much am i looking at and from where? i have priced some from overseas and can get a LUK clutch kit landed here for about $AU200. just wondering how much they are locally.

this is my daily not a project hense my reluctance to spend too much money on it, just after a cheap fix. even though i love this car and it has been bullit proof reliable:bowdown:

cheers
john