Hi all - Thanks for all the input. The fans have been rewired running a separate feed. Also the loom is new and the injectors run an independent feed/relay system eliminating voltage drop at high boost. The fans are relatively new and draw 8amps. Alternator new pos cable and a string of unrated earthing points there is Zero differencial.
Its interesting!
Oh car is not in the UK or I would have been to see stu quite a while ago! Took me forever hunting down a misfire @24psi. Replaced all the usual bits over a period of a couple of years then oil consumption started rising. So took the engine apart and found the inner valve spring on number 4 exhaust broken and a completely missing the stem seal.
valve bounce/oil consumption!! job done.

Thanks all


Tim