Where would I find a BSP tap? Does anyone know?

I am trying to tap the hole where the wastegate arm went through so I can put a plug in it.

A 5/8-18 NF makes slight cuts in the metal. I am actually trying to find one that will match the plugs in the oil filter housing. It will fit perfect if I can find a tap to match it.

BSP is a British Pipe thread, are you sure thats what it is? Or do you mean NPT (national pipe thread) the standard kind

It is the same size as the oil line on a 2G. It has a hard line that runs the turbo. And it threads into the oil pump housing. I thought it would be a BSP but I could be wrong. I do know that the 5/8 that I got the threads are a c hair off.
I am also thinking that I may have to drill it out and then tap it bigger.

It's probably BSP, everything is metric. You'll have a hell of a time finding a BSP in a local store, best bet is the internet.

I would just drill and tap it for NPT to make your life easier.

ya, your best bet would be drill it out bigger.
just go with an NPT size, that way you can get a pipe plug to plug it with, But watch out when you tap it, NPT taps are tapered, if you go too deep the pipe plug wont grab any threads.
A good rule of thumb is to go 10 complete rotations with the tap once its drilled with the correct sized tap drill.

Hey I got it!

This is what I had to do. After removing the wastegate arm I pushed the sleeve out that is in there. Then I went and got a 3/8-18 npt tap! This tap is perfect for this hole. You can use the fitting out of the oil pump. It is the same as a 3/8 pipe thread plug. So that is it I taped it out and then put the plug from the oil pump in it. It is a much cleaner look!

My next question would be Plumbers Tape or JB Weld for the plug!

I wouldn't do either. The heat from the exhaust will bake/burn it out. The threads themselves should seal fine.

Great! It is done then! Thanks for all the help guys.