A 4psi or 6psi wastegate spring won't make much difference to me as i'll probably run a minimum of 8psi of boost anyway, but with the 4psi at least i'd have the option to drop the boost right down if required at some point.

Always good to hear peoples opinions on things though, so thanks for the input guys

and if you're interested this is what 8psi goes like with a passenger in the car