Update Well, I'm no closer to finding the issue. Removed the EMB, set the timing back to 8-10 degrees, fitted stock injectors and it's still got the same lag/over boosting issue. The first problem I need to fix is the boost control. I've removed the TiAL waste gate and took the car for a run, it still makes 0.25 bar of boost. I believe it should make no boost at all so that rules out a faulty waste gate. Removed the turbo, everything looks fine and the waste gate penny flap is welded shut with no visible leaks. Next step is possibly try a different manifold set up as the old ram horn kit was working and boosting perfectly!