I was back at MRC today and we resolved the high-rpm issue.
MRC can now finalise the tune, now that they can hit the redline every time.
Once that's done (maybe even tomorrow if I'm lucky), then I'll finally get my car back!

What was the issue in the end?

just_ace
What was the issue in the end?

 
As expected, the issue was the width of the teeth on the 60-2 wheel.

I was having trouble getting email responses from RacerX (which is unusual), and I was sick of paying for shipping from the US, so I decided to design my own 36-1 crank trigger wheel in CAD and had it laser-cut locally. The teeth are about 40% wider than those on the 60-2 wheel.
The NUMBER of teeth on the 60-2 wheel was never a problem, it was just the WIDTH of the teeth. At high RPM (~6700rpm) they became just marginally too narrow to provide a reliable signal from the hall effect sensor. Actually, I should also mention that the first 1 or 2 dyno runs were always OK to the redline, but then it would always misbehave after that, so it's probably somehow temperature-related too.
I could have designed a 60-2 wheel with slightly wider teeth, or it may have been possible to somehow make the existing 60-2 wheel work, but it was easier to reduce the number of teeth so I could make them significantly larger and be confident that the problem would be solved. Besides, 36 teeth is still plenty!

With the issue resolved, I can't wait to see you crack the 300 mark :D
 

It's time for a dyno graph!
 
The result (on 98 premium fuel) is:
300.8rwkw at 24psi, dropping down to no less than 292.5rwkw with higher ambient temperature.
 
The little dip in the power curve at high RPM in the first plot was due to the issue that I previously mentioned, which was resolved when I changed the crank trigger wheel.

 

  
I went for a good drive on the way home from MRC, and the car feels so damn good!
The GTX3076R sounds ridiculously good, from as low as 2000rpm. I don't know if it's mainly due to the new compressor wheel or the anti-surge housing.
The OS Giken R2CD twin plate clutch is much nicer than I expected it to be, which I'm very happy about too.
 

 
The E85 tune will happen next year.

You gotta record and post a sound file of the spool, the afterglow we don't want to know...
 
Looking forwards to your track day smirk!
 
Congrats for hitting your target Rob - next will be your mrs goals of mortgage and family!!

that is pretty awesome

So how does it compare to response than the ol 3082 setup?

Awesome power gain.

Congrats on the result!

Thanks guys!

just_ace
So how does it compare to response than the ol 3082 setup?

It passes 20psi of boost at about the same RPM or maybe 100-200rpm sooner than the 3082 did. As expected the 6mm smaller compressor wheel partially makes up for the loss of response from the bigger exhaust A/R.
It's hard to tell because I hadn't driven the car for 5 months before today, but it 'feels' more insanely torquey between 3500 and 5000 rpm.