Hi there I have a 2003 Octavia vrs estate , I had it tuned at Celtic tuning about 9months ago and it was running lovely . Since the map I have fitted a CAI , extra large tip , fmic , and done n249 sai delete . A couple of times I've had intermittent boosting . Now the boost has dropped from 18psi holding at 14 psi , to 12 psi holding at 10 psi . The maf is fine , ive got a new uprated fuel pump on order . Could it be the n75 that's gone ? Any help would be very much appreciated .

Boost

I'm assuming you have done the basics already like checking for boost leaks including vac lines?

Could be the N75, do you know anyone local who has an 1.8T who would be happy for you to try their N75 to rule yours out?

I've checked all pipes and can't find any leaks only by looking though , is there another way to check ? My boost gauge is reading -18 psi on tickover . Dont know of anyone close who has one .

Fixed my problem , fpr pipe to intake manifold had a very tiny slit in it and that was causing me to lose the boost . Crazy how such a small thing can make such a huge difference . Boooooooost !!!!!!!!