Exhaust Heat Wrap
Dave (Last Minute Racing) suggested that I try a heat wrap here
Googled this place to buy it from:
http://www.thermalvelocity.com.au/Exhaust-Wraps-/G-Force-Wrap-/p-105-409/
And ordered G Force Wrap 50mm (2") x 10m (30ft) + 10 X SST
Installed it as per the instructions - looks a bit messy because of the varying diameter. I found I could twist it as I wrapped to go around tight bends more evenly. Definitely wear gloves and it probably pays to get a box of latex ones that fit your hands. Only one pair came with the kit and they were of average size which broke as I put them on.
We'll see next if it does anything to the dyno result!
Conclusion
9/2/2012 Update - for the following we found in another run the jetting was lean, so power might have improved with jetting changes. The proper way to test is jet correctly-> dyno -> wrap -> jet correctly -> dyno -> compare results
OK dyno'd the exhaust wrap tonight with some interesting results...