also size of turbo to engine capacity driving it as the amount of exhaust gases will be greater on a larger capacity engine so will spin up a turbo quicker than the same turbo bolted onto a engine with 500cc less capacity

ie:

std t3 on 1600cc cvh turbo engine about 3.5k revs

std t3 on 2100cc zvh turbo engine about 2.5k revs

this is what i found quite some time ago