what wastegate?
 

i am deciding on what size and brand wastegate i want to go with, is the any formula i should follow to determine what size i should get? and i was looking at tial and the new synapse syncronic ones also.

think about what you want to limit your boost at and go from there, in my turbo kit im building i wanna reach a peak of around 17psi therefor i am running a 1.2 bar tial 44mm.

What turbo?