Well, my sidepipes are now re-packed (with a new three layer approach - first a layer of s/steel wire wool to stop the packing blowing out, then a layer of basalt loose packing, and finally a single layer of glass fibre matting to hold it all in place while the assembly is slid back into the pipe). They sound great now.
My replacement dizzy to coil lead arrived at long last too thanks to Philip Brodie of fuelcat.co.uk, so that's now fitted. Plus a rather nifty two-tone
Stebel Nautilus twin air horn to replace the previous "road runner meep meep" type horns. A great improvement - I'd say the horn and the sidepipes are probably now both pushing out 110 dB!
So it's a long test drive tomorrow. I haven't decided where I'm off to yet though. As it's a Bank Holiday weekend, I'll probably hit the A34 southbound then see how crowded the roads are and just follow my nose - safe in the knowledge that my trusty TomTom won't let me get lost!