The Diff ratio was 4.11, although I am now looking at going to something more like a 3.7..... this may also help with the power down by using the torque of the engine more so than it is now.
The diff is a NIZMO LSD...... I am hoping to be able to repair it. If it can be repaired, I will probably sell it off - with the axles to suit and replace with something a little stronger (hopefully).
Something else to keep in mind, the car comes on boost before it starts getting noisy. When the engine starts sounding "angry" the waste gate is open. The reason the tone changes so uch is the screamer pipe off the external gate

.... I love that Sound! It finally sounds like a race car!