areas

I have had my car checked by 3 garages, they cannot locate any leaks, No pressure tests have been done, just visibly looking at the hoses, Leak started when I changed to an uprated recirc DV, A huge wheezing can now be heard with probs only 75% power.. Where should I be looking for leaks...

Wondering if anybody in these areas has vagcom? Ive got my 40k service at SEAT begining of Feb & hope to sort my problems out then too. Car is running very rich at present causing loss of power. I could really do with somebody that has a spare hour to hook Vagcom up to my car to check for...