Combo is 306, edel. perf heads, Lunati 51014 cam, Holley intake and MP t-70.

I have a TiAL 38mm with 10psi spring, and it will hold 10psi till 4k rpm. Then spikes to 16, down to 9, back up to 16 and and back to 9. This happens between 4k rpm and 5k rpm. I havnt went past 5k prm yet. Some say the wg is too small, but it seems to be able to regulate after the spikes. Boost ref is coming from Right after the compressor. Run a 8psi spring and use a MBC set to 12?

 

So are you running a boost controller set at 12? What happens when you simply run the WG with the 8# spring? If you're running the MBC, remove it and see how the car runs simply off the gate set to 8, or 10, whichever spring you have available.

 

What i described is just running the 10 spring, no controller. I was thinking of using an 8psi spring and MBC set to 12 as a possible solution.

 

Get rid of the controller and run the spring alone until you find the issue. See if the problem exists only using the 8psi spring...

 

I'm running the old style 35 mm and have no probs on a stock 302 at 10psi. The angle and positioning of the wastegate have alot to do with boost spikes. You want the pipe to the wastegate to be at a 45* angle to the flow into the turbine. If you have it on the crossover tube then your only draining one bank of cylinders and that can fuck with it like your seeing.

 

I was NOT using a controller. Just a 10 psi spring.

 

The wg is positioned at an optimal point right before the turbine.

 

Then you're going to need a bigger one
issuez

 

My PTK kit had the WG right at the turbine housing too, but it was 180 deg from exhaust flow. How is yours WG oriented relative to exhaust flow? If you dont have a pic, just do a cheezy MS paint.