Aye Mutt,
Commiserations!
Having never owned an XBR or dealt with it's studs, I make no comment about whether to do the job in situ or on the bench.
However, if you are going to have a crack at it yourself, I would suggest that you use a good sharp set (new) of left-hand twist drills to remove the stud, rather than 'Easy-Outs' etc. The left-hand thread drills are not only removing the stud, but also trying to 'undo' the stud at the same time. Plenty of PlusGas 'A' applied before and during the operation helps.
Also have a quality plug tap of the correct size to clean up the threads. Use either OME studs or frabicate your own from stainless steel, threaded rod. Use stud lock to lock the stud in place. Then apply plenty of copper grease when assembling the exhaust collars and nuts. Domed stainless nuts are preferred, but be aware that cheaper ones may not have well formed threads during manufacture and either will not thread far enough down the stud to hold the exhaust header tight against the copper 'O'ring in the head; or are insufficiently deep enough to do the same!
Using phosphor bronze nuts or stainless steel locking nuts, again with plenty of copper grease is an alternative.
SRX's have similar problems!
I hope this helps.
My regards, Bill