Here is a log showing my boost profile with the Halman MBC used on the lower nipple of my Tial 40mm Wastegate.





I am wondering if the springs you use in your Tial wastegate are jacked up. You said they are not actually from Tial correct? Our engine setups are virtually identical other than wastegate size, and that I run alcohol injection without ever running leaded race gas.... and as you can see from my log my boost is steady as a rock down at the 28 to 30 psi range. Do you get that horrible spike and drop off even at lower bost levels?

Keith

 

Lower nipple "normal" style with a Hallman Pro.

I was thinking that it may be the strange springs in it... I also thought perhaps my boost controller wasn't so happy.

Yes the boost still spikes at lower boost... it will go from around 21 to 19. I think I do have a few true Tial springs but I dont know if any combination of those will hit low 30s.

 

Well I swapped the springs to true Tial springs and it still spikes even at lower boost (21 -> 19).