I've read back over the thread but Can't see it. I could have been sure that you posted that you had water ingress in the front foot wells.
As for cheap mods they're not really cheap. Bigger injectors and a remap is about it but with that turbo I think 135 bhp is about max. Injectors can be found at darkside developments and I'm not to sure who wound do a remap for you in England. Price is min £340 if you fit the nozzles yourself and more if you have to get them fitted.
I like the sound of seatmann's tuner that is listed in his signature. Try him.
£300 max from project-power.co.uk
Doesn't take a straight map either, ecu needs chipped, it's an MSA15 I think it's called, that's the reason I went with bigger injectors in the first place.