Are you using the actuator that came with the turbo?
They arent the greatest, quite soft and creep open a bit, that's probably causing the slow boost.
I got one for a mate for his 3076 from USA, 14psi spring. The overall size was larger, and it was tight as buggery compared to the "stock" actuator. (when doing the old "pull on this" trick)
PM "Lithium" and ask him a question or two. Hes tried a few different approaches to the spool issues.