I have a TiAl 35mm external wastegate. For some reason the bolt that goes on top of it is missing (which is what assume can control the boost). Is that bolt some kind of special bolt specialy made for that wastegate or can find a regular bolt that fits and use that instead? -Thanks-

 

the hole stay open, or unplugged, or whatever you want to call it, until you put a boost controller on it, then it has a little nipple that screw into the top

 

It's a 1/8" NPT thread. You can buy an Earls 1/8"NPT to hose barb fitting for it.