Imho with all the stuff you've changed to get more power out of the engine, i would take it to a tuning shop with an RR and have them remap the car properly for the hardware you are running. That will sort it out as they'll soon notice the turbo isn't boosting right and they'll dial the lot in right. you'll probably endup with more power too so it's a win win. It might be expensive but once you've changed so much you can't expect a generic fadr ecu to take into account the way the turbo boosts especially if it's not set right from the get go. Also your not the first to experience the x-man turbo not being setup right, i have read more people omplain about it but usually it is the sheer amount of changes of hardware for more go that makes it worse.