Wallace - Heard many bad things about them in the past but since Russ started, they've got a better rep. Evo boys up here use them fairly frequently with good results.

Japerformance (Aberdeenshire) - Wouldn't use them. Horror stories galore but may be OK for a power run.

AVA - Obviously good at what they do but always gave me the impression they were out to make a buck. Took my 1.9 RST down and they basically said it would need to £1500 spent on it. "We'll do it now if you want?". Answer was no, car was fine for months and I was £60 down for them just to tan it on the rollers!
Similar experience to Carlo by the sounds of it.

N/A Tuner - Ricky Gauld in Aberdeenshire used to be famed for his N/A Tuning. Heard he'd packed up recently though, but its never been confirmed.

Hope that helps.