for about 3 months now my car looses boost after 4.5k rpm. i always had my greddy profec set at .8bar. i used to see it hit consistant 12-13 psi all the way to redline. for 3 monts now it peaks at little over 10 then drops gradually after 4.5k rpm, to about 8-7 psi.
another problem is recently, i would be cruising at just 2.5k rpm in say 2nd or 3rd gear, then feel the car getting weak. so i would add more gas, only to hear the turbo spool up and see the egt rise, and so will boost, but the car wouldnt really move much. happens for and instant when it does... im not sure if its me or maybe its related to the problem above...
also when im cruising on vacum, i would see the psi needle like fluctuate really really fast up and down, like + or - 2 psi. im not sure if thats normal tho...
thanks for the help.