hi just brought a audi a3 05 model 130k full audi service history been well looked after owned by a old couple for last 6 years all seemed drives perfect until 80mph then the turbo cuts out switch engine off an back on again perfect again till you get to 80 agen then same thing every time engine manegment came on and says overboost proble any 1 have any ideas tried asking previous owner but said they never drove it that fast so didnt no about the problem like i say it is only when you hit 80mph the turbo cuts out can any one help thanke