Hiya. Me and a friend fitted a dump valve to his 96 STi the other day. We checked every thing twice, made sure it was all tight etc. Took it for a test drive and the valve made little/no noise. After reaching 70mph the car lost power. We took it to Exeter subaru who informed us that a piston had blown! He's a trained mechanic so we're a bit puzzled as to what we did wrong. He's done a fair bit of work on turbos and we had the instructions for it. The thing is ive just bought my first WRX and want to fit one. Does any one know what the problem might have been and hiw do I avoid doing the same???

 

Sounds to me mate like you managed to create a boost leak somwhere mate, this would cause youre mota to run lean... thus the melted piston.

Sorry to hear that, hope you get it sorted