The car has been running OK until last night when, with outside air temp noticeably cooler, slight hesitation has returned when giving it stick in fourth or fifth. Same thing happened last year and two MAF sensors and one lambda sensor later it appeared to have gone but that was April'ish and the air temp was warming up anyway. Car is a UK MY00 with PPP, a Roger Clark 3" downpipe with sports cat, a ZeroSports intercooler splitter and 67,000 miles showing. The MAF sensor, Lambda sensor, HT leads and plugs (PFR7B gapped at 0.6mm) are all recent. I have previously cleaned out the vacuum piping and boost control solenoid. I'm wondering if there really is a fault on this car or if the downpipe is allowing the turbo to spool up quick enough to create slight overboosting. I'm wondering if fitting a manual boost controller would be a good or potentially fatal solution?
Kevin

 

might be just the boost is coming in harder when it does cos of cooler air temp

 

The colder it is the more power you create due to it being more dense, sumut like that anyway