many thanks for reply, i think injectors 3 & 4 seem to be main culprits, noise seems most evident in that area.

i have had rocker cover off, and all looks OK in there - thankfully!

if those injectors were at fault would the noise tend to quieten down as revs increase, my engine seems so much quieter at 2,000 upwards. and if i rev it stationary i can hear noise come back again as revs fall.

De-catted i could feel an immediate improvement in throttle response, certainly lets turbo spin up faster, not sure how much of a power increase i have. i was surprised how low the exhaust emmissions were at mot time too!

E39 alloys were just off a 1998 525 SE, so nothing special, still 15", but to me improve look of car, im still on the look out for some 17" alloys off a E39 though