Ok so I might not take it to roll racing just yet. I did a trans service today, mainly to see what the fluid looked like. It wasn't great and there was a bit of a sheen to it, like when bushes are wearing or something metallic is wearing. No chunks in the pan and it still shifts fine but considering the extra fuel use, I'm gonna pull the box out and see what's up. As I've said I reckon it's a converter issue but all that will be checked out shortly.
Fark me ay, rebuild the engine, get a haltech and I still can't drive the farken thing.