I think you're running too rich. You lude injectors are 270cc/min right? Or are they still 240cc/min for your car?

If they're 270cc/min then drop those in. I think you're car is bogging down and running super rich. The turbine housing may be a bit too small, but leanning out your a/f mixture is an easy and fast fix to your problem. If you're running 310cc injectors at 5:1 in the FMU then tone down the injectors to 270cc or 240cc and don't boost over 6psi. I'd put money down on it that you're running like 8:1 in the A/F range. I know I'm running to rich at about 10:1. Unless you decide to scrap the turbo (which would be stupid) and go with lots of nitrous then you won't need an A/F ratio of 8:1.

Try leaning it out. Put in smaller injectors, lower the idle fuel pressure to about 36psi, and see what happens.