You have to take into account of what size turbo you are using.
If you are using a small turbo with high boost pressure you would require a large external wastegate.
If you have a large turbo you proberly dont need a large wastegate!

You have to think how boost pressure you want. In respect of how much exhaust gas you want to harness or to bypass the turbine wheel.

Proberly doesnt make sence!

My application is a small turbine housing combined with 2.0l engine = lots of exhaust gas to block up the turbo so fitted a large wastegate.

S.