The stator plate on those have a notch on them. You can adjust the timing by adjusting the position of that notch.
A biturbo might give you a mile on topend.
You can go to a smaller rear sproket also.
That one probably already has a 22, so you can do a 20 without too much work. I'm thinking of going to a 2. They call it a stick sproket, VERY fast.