my car has a rattle at 3500rpm+ in 4th and 5th, i was speaking to rob(16vastra) on msn and he thinks it might be pinking, but i went out in it today and it doesnt sound like a 'plink' type noise, more of a scraping of plastics/metal type noise, and it sounds like its comming from behind the dash too, i know for a fact that my heat shield is only held on by 2 bolts as one has snapped in the head and i can hear this if i rev it on the driveway.
just to add in using esso sul and i know that the timing has been advanced a further 5 degrees at WOT by steve at sbd to run on sul.
the XE exhaust makes that sort of noise at those sorts of revs. also both i and mattj have had annoying resonating buzzing noises, both pinned down to cracked heat shield. i did something simple to rule out pinking, i turned the fuel pressure up to 70psi and went round the block. not only did hoses not pop off, but it still rasped.
well been out tonight, still seems to be doing it, ive removed the heat shield and still does it, but as i said before its not got any pattern to it, ill give the fuel pressure and upping tommorrow to about 60 psi and see if that helps