question, If the wastegate comes with a 4,6,8,10 spring. which is best to be used on a stock vf39? or a fp green? and have good boost? thanks

 

You will need a combination of them, I believe .9 bar for a 38mm and 1 bar for 44mm wastegate.

 

lets say its a 38mm wastegate. so i would use a 8? since it didnt come with a 9?

 

.9 bar = 13.053 psi. Try to get as close to that as you can. Your tuner will be able to dial it in from there. I think my tial came with 6 springs, I hooked it up to my pressure calibrator at work to verify, mine opened around ~12.5psi IIRC.

 

so the higher the spring, the higher the boost? higher spring means more stiff? correct?

 

FYI there is a guide on Tial's website to help you with situations like this:

TiAL Sport.com