Duncan, the OP is asking about turbos to go on an engine that won't be opened up.
I agree that if you are looking at over 400 then you may as well nudge 500, but that is another question.
I've seen answers on what the standard short engine can take as anything from 350-450ish, but there are exceptions at each end of this range.
As already said, i'm not pulling apart my engine and want to push further than a ported VF43.
The choices (to me) are a TD05/20g (on costs grounds) or an MD321 variant (too pricey and slightly over spec).
I've jumped onto the 20g, but is there another turbo that Damocell should consider, given his objective?
nick