I meant to say following my visit: you might want to revisit the intercooler size. Thinking back, it looked pretty big for the spec of the turbo. My (petrol) Forester S Turbo has one a fraction of the capacity and the engine puts out 50% or so more power. My smart Roadster puts out 113bhp but has a cooler the size of a stamp.
Intercoolers are a balancing act like everything else: on the one hand you want to cool the charge, but go too big and your throttle response can be compromised. I imagine that the turbo has to effectively raise the pressure in the whole charge cooler before the engine sees much of a rise in charge pressure. Effectively it's an air cushion: the opposite of what you want. The huge advantage of the little turbo currently fitted is it should spool up very, very quickly and just give you that lovely big-engined feel. This gain could potentially be undone with a mis-matched cooler potentially leaving you with turbo lag but without the big power of a large turbo either.
You might want to investigate the merits of a smaller cooler and possibly, shorter pipes if possible. At the very least, perhaps see what that turbo would have run through in its original setting. Either that or get the turbo type and see if there are some specs to match it to.
Get it right and you should end up with the advantages of the turbo with most of the advantages of the standard car and a very 'sweet' driving experience: i.e. a seamless power delivery from light throttle / low revs all the way up and through to wide open throttle (WOT) and full revs. I can see it becoming a popular mod! As turbo cars normally run lower compression ratios, the small turbo, light boost is probably a very effective and pragmatic mod.
Somewhere I've got a book on charging, bought when I was considering building a super-charged TR6 donor for my 1950's style Italian'esq ally coupe project (relegated back to pipe-dream status after two car designers plus me failed to reach a suitable shape
)
I take it you'll be running a Pro-Boost btw? Can you remind me what the spec on the turbo is?