I was wondering why my car has started surging. Not too long ago I had a Milltek exhaust fitted but have just noticed that if i am at low RPM and I accelerate hard in a high gear like 3rd....as the car reaches maximum boost it surges where boost drops in and out. My car is remapped by AMD so the boost is at about 15-16 PSI....as the boost drops in and out so does the power and the needle on the boost gauge flicks up and down. Any ideas would be greatly appreciated..