I have a kbracing setup on my truck with a 50mm jgs wastegate. We were tuning the truck and were going to shoot for 18lbs, the truck was holding at 14lbs through first second and when the converter locked in second, when it shifted to third it spiked to like 19lbs. It has always spiked alittle but now is excessive since I am trying to turn it up. I have a line with full intake pressure to the bottom and a line with an adjustable regulator running to the top. Is there anything I can do different to help eliminate that much of a spike or am I going to have to move the wastegate to under ther turbo?

 

I went ahead and put mine under the turbo=steady 13psi with a small precision gate.

 

Do you have any pictures by chance?

 

This is where I have mine, and mine spikes like a SOB too!! I have mine setup just like you say yours is and mine also only runs into this problem on higher boost as well. On my first pass at the track it held a steady 7-8 psi in ALL gears but when I turned it up to 12 psi it worked fine in 1st and 2nd but when it hit 3rd it went to 15!! VERY frustrating because I've got it tuned to pull alot of timing and go rich after 14, it hurt my MPH at the track. My gate is a 46mm and the rest is in my signature.