What sort of boost is achievable with the later uprated efini twin turbo packs (as seen here (http://www.rx7.com/store/rx7/fdturbo.html) ).
Also any UK suppliers for a resonable price?
You should be able to run 1-1.1 Bar (14.4-16 psi) of boost. Not sure where you would find them in the UK tho.
Fish