MAMBA TURBO OVERBOOST

[elsk]

How's it going everyone,

 

Having a bit of trouble on my Mamba GTX3071 with .73 rear housing on my rb25.
I've got the 18psi spring in the wastegate, but for some reason it wants to boost boost over 25psi, it doesn't seem like it wants to stop?
It holds smooth until about 4500 rpm then goes crazy.

 Things I've tried:

- Went from split dump to bell mouth dump (didn't help)
- Shoved compressed air in wastegate to make sure it opens (it opens)
- Filmed the wastegate while driving (it opens)
- Boost leak tests (no leaks)
- Tried weaker spring, tried stronger spring (still over boosts)

Has anyone had this type of problem with these turbos before?
Saw a video where SAMMIT ported out the wastegate hole, but to me it looks like it's quite large already?

[Dose Pipe Sutututu]

Yeah you'll need to port out the wastegate hole and run a larger flap (if possible), alternative is to just weld up the wastegate port and run a gate off the stock manifold (don't delete the stock divider).