Hey, I'm looking at converting a t3 iv got for a 2l Zetec turbo conversion I'm looking at doing to be able to use an external wastegate rather than the internal one. I'm pretty confident about doing the welding and machining back as my dads a professional welder and has a mate who can machine it. My main question is how do I work out which psi wastegate will I need?

I know there's a big arguement between if it's worth it bla bla but to be honest iv decided I need a screamer pipe in my life lol!

Has anyone got or used an EW got any advice?