hi all, problem with me mates fiesta rs turbo. his car wasn't boosting very strongly at all and when i fitted a gauge was barely making 5psi ( it's totally standard by the way ) so i fitted him a new actuator today and when i first drove it it was spot on but the boost was 0.8 bar and when we got onto the highway the overboost cut in when we were in 4th. let it cool down and then adjusted the actuator and it was pretty much spot on ( peaked at 0.6 psi and then held at 0.5 ) trouble is the ignition started cutting when the car came on boost ( it felt like the overboost cutting in again but it happened straight away as soon as the car came on boost, on other rs turbo's i've only ever known the overboost cutting in when there was more load , i.e when planting your foot in fifth or running full throttle in third or fourth ) the car does run on the hot side and i would imagine a little hotter still now the turbo is doing as it should, which makes me think it could be heat related? i know you can get missfires etc with excessive heat but would it cut the ignition?

any pointers would be great people and solutions even better !!!

thanks for your time