My manifold is set for a 50mm wastegate. I want to know if I can run a 46mm instead of the 50mm?

 

why not do it right?

 

those that mean just go with the 50mm?

 

What type of turbo? whats size BOV? Are asking this question because you already have the smaller wastegate?

 

T-76, no bov yet, all I have is the turbo and manifold. working on building a setup and the manifold has a 50mm 4 bolt hole for the wastegate.

 

What size turbine are you running? p trim? If you are using a p trim turbine with large a/r like 1.05 or larger then the 46mm will be fine for controlling boost modest to high boost.
but if you are intending to run a larger turbine trim or smaller a/r like .84 then you will need larger wastegate. The smaller a/r will have greater shaft speed so it will put more work load on the wastegate. Also larger turbine trims make the valve area on the wastegate less affective so you will be best to use largest wastegate option with large turbines.