Just purhased bugera 333xl head and cab. Been playing for a few days, but find the lead channel to be very muddy and unclear. Quite grainy distortion rather than the punchy sorta metallica tone im after. (I have fiddled the EQ and gain btw, im quite a tone freak and know wot im doing in that department :P ).

Just wonder if perhaps its my ibanez rg standard pickups that are due for a change to something higher output? Or if perhaps a problem with the amp? Or i need to buy a pedal? (pickups are on my wishlist anyway ) Any advice is massively appreciated!
You know that the 333XL has an active EQ right? So it acts differently from the passive EQ that you would find on most amplifiers. I would try leaving the Treble and Bass at noon, then drop the mids just a touch. Also, have you been able to turn it up at least to where it opens up a little? That could be another issue, because it will sound like a blanket is over the amp (fizzy/muddy gain) until you turn it up a little. This amp had no issue getting Metallica tone when I was playing around with it.

Beyond that, you could look at new preamp tubes (I recommend JJ's and Tung-sols), Throw a EMG set in your guitar, or buy a tubescreamer.
Do you run anything in the effects loop? My decimator sorted a similar issue out with my 6505 along with putting a tubescreamer in front of it.

The pickups would probably have somehting to do with it as well, a tube amp will usually accentuate the nuances of a pickup so if they're quite muddy or bassy that would be amplified (no pun intended) by a tube amp.
Fender Jim Root Signature Telecaster
Martin Westside Custom Edition
Peavey 6505
Peavey XXX Cab
ISP Decimator Prorack G
Sennheiser EW172 G3
Sennheiser wireless IEM
Ibanez TS9DX
Boss TU-2 Tuner
wow u guys know ur stuff . I guess in all honesty it is being run at relatively low volumes, but i shall be investing in sum new pickups, possibly sum JB's o livewires, dno if i wana go over into active territory. I can understand how having it low could do that tho.
Before you go out buying anything I would crank the sucker just to know what the amp is capable of. If you get the volume up to 4-6 and your still not happy with what your hear, them my first purchase would be an tube screamer (I would recommend the Maxon OD808) to set as a clean boost, followed by new pickups, then new tubes.
Sig What?