Got a wrx with a vf35 turbo. Anythin over a bar of boost and its run ****e. Juddering and boost gauge is bouncing about lk mad.
Any ideas?

 

So hard to diagnose over the Internet. Could be many things.
Would start with the easy stuff first like boost leaks and checking all the pipe work ect. Best to get a mapper to do a diagnostic check.

 

Check the dump valve and vacuum tubing, also general leaks in the intake system. I believe my dump valve is causing unstable boost for me too so I've bought a HKS BOV that uses the boost pressure to hold it shut rather than a spring like most.

 

Is it setup to run over a bar of boost fueling ect?