@AJP Ill report back, hopefully tomorrow, if I get a chance to make the swap back to the old dv tonight.
Googling for "boost leak test cambridge" or similar reveals no obvious results. I think this in itself is quite strange, considering the number of cars going about with turbochargers fitted these days. A couple of garages I have spoken to say they manage to find leaks without any way of pressurising the system. I mean, I can understand If a leak is obvious (e.g. a pipe dropped off) then this is the case, but who's to say any given charge air system couldn't have hard-to-see leaks affecting performance (maybe like I am experiencing, or even to a lesser degree). Would have thought some system to test for this would be bread and butter these days.
Thanks for the recommendations, I'll bear them in mind.
@Pudding the dv+ will be the way I go if it does in fact turn out to be the culprit. I have old boost logs from just before the revC came out showing It was fine before preemptive replacement, If boost is fine after going back in, ill leave it that way til I can get a dv+. If it still makes no difference, the revG will be going back in before seeking professional assistance(for both the car and my mental state, at this rate..)!