spiking with a 50 trim

[spoolinspyder]

i have been trying to figure this out for a long time now. i have a 50 trim turbo with all the supporting mods and a joe p mbc and no boost leaks at 20-25lbs. my problem is that i can never seem to hold my desired boost level of 20lbs. Boost always seems to drop down to 16-17 psi range in 2nd, 3rd gears. i have a vp o2 housing with no boost creep issues, only spike. im thinking about purchasing an external wastegate to help splve my problem, but I really dont want to spend that much cash to get the same results. I've read about wastegates being blown open, so thats what im assuming, correct me if im wrong. The turbo spools great and spins freely, but cuold it be the MBC? My boost holds 20lbs fine in 4th and 5th, but i could care less about those gears. It tends to drop aroound the 5500-higher range so thats why i think its the wastegate being blown open= too much exhaust pressure. Let me know what you guys think cuz i cany get a decent tune without boost holding steady

 

[44pirate]

Do you have an adjustable actuator arm. If so tighten it up a bit.

 

[spoolinspyder]

i tried pre-loading the wastegate actuator with shims to hold it shut tighter, but still does it. i tried tightening it up but i still got the prob. thanks for your reply