hi all About 4 months ago I started modifying my 2004 ba xr6 turbo, starting with exhaust an high flow cat, than I got upgraded injectors installed an tuned ( siemens deka 60lb) I also got my gearbox rebuilt by MVAutomatics stage2, it didnt make much power with the first tune (203rwkw) my tuner said I needed heavy duty valve springs so I bought plazmaman valve springs and got them installed and retuned....PROBLEMS THAN STARTED) the car made (249rwkw) but was playing up.....the car wouldnt boost properly and after hitting boost felt like it was dropping a cylinder if not too, would run rough for 10 or so seconds than run fine, took it bak to my tuner an he said ok it needs upgraded wastegate and actuator plus boost controller, so going with his advice we went ahead with all that not stinting on anything...got all that installed and retuned again it made (279rwkw) current on 15 psi but had the same problems there so took it bak again and said not right, my tuner checked the tune again and found that the torque management setting was causing the boost issue so he turned that off and fixed the boosting issue, huts 15.5 psi had and holds fine but still have the problem after boost dropping cylinders or what ever its doing, Ive rang turbosmart too see if it was a boost issue, nope tested all that, we have changed lifters, dudnt fix problem, changed standard valve springs back over still does it, pressure tested motor, fuel system, air tested valves, pulse tested injectors, spark tested coils, plugs and coils are brand new and plugs been gapped to.08??? the're at a loss so am I..HELP PLEASE