Driving me mad! 
Convinced it must be related to the intercooler, I stripped it all off, found nothing loose, but the heat shield touching the near side support bracket which when provoked gave what I was certain was the cause of the rattle. Isolating pads installed, suspected noise cured, re-assembled.
Start it up, hold revs at 2k…RATTLE!
Arrrgggghhhhh!!!
/ Love my car really, just wish it would only make noises it’s supposed to!
Broken supercharger support bracket to the gearbox? Those heat shield resonate on there own as well, stick a lump of sound deadener in the middle of it, that will stop it vibrating on it’s own.
I plan to get BoT or someone to track it down whilst revs are held.
Only happens between 2&2.5k revs, perfect at all other times!
I have similar mine seems to be 2.5-3k and it drives me mad haha. Haven’t had a chance to track it down yet though as pretty busy at work so haven’t had any spare time.
Sc bracket was upgraded in later years. .
cost about 80 f…ing quid ! !
Well that’s two of you that have mentioned it now, so would seem like a good place to start!
Accessed from below or above?
Below …on your back , crawl underneath the raised car with undertray removed and you’ll see if its broken or not.
FIXED! 
So…an hour and half of Jezs time at Back-on-Track, and he wouldn’t give up until he found it.
When I got there, lo and behold the rattle had cured itself, but we decided to take the trays off and look for loose items just in case.
SC bracket? Nope. Not broken, tight as a tight thing, and I have the later variant it transpires.
We tapped as many things as possible, and the clear suspect was the exhaust ‘U’ bend heat shield, so a modification was carried out to eliminate that.
Also found that the exhaust was a little bit loose, rotating at the bracket to ‘U’ bend end, with a tell tale scratch on the exhaust tip where it had been touching the diffuser aperture. All nipped up and another suspect eliminated.
All reassembled, and job done or so we thought…
I drove less than half a mile down the road, and the rattle was still there as loud as ever!
So back to the work shop I went (by this time I’d kept Jez longer than hoped).
Luckily this time I could replicate the rattle by holding the revs at 2.25k, and it honestly sounded like a penny/stone bouncing up and down beneath the drivers or passenger seat - which it wasn’t! But we were getting closer…much tapping ensued with undertrays in place…
Jezs expert diagnosis was that the forward edge of the central undertray was the problem, so it was removed, and true enough the applied foam wasn’t engaging in the chassis join as well as it could! Undertray removed, foam re-secured, and undertray reinstalled. Rattle gone!
Never under estimate the importance of foam! 
Glad you’ve already got the beefy bracket cos 80 odd quid is pricey for what it is 
Good news Pete
Had exactl;y the same issue on mine a few weks ago. U bend clamp was loose and heat shield was vibrating a good un. Jez did a good job fixing that but in my case it was fairly obvious!!
Hats off to the BoT crew once again!