The noise that I can hear inside the car, sounds like the flow of air is disrupted (very quickly) and then freed up (very quickly) creating the flutter. I think it's definately something with the wastegate/ABC system.
I've got UTEC, and I did adjust the ABC last night, seemed to help a bit. When I first installed the UTEC with my other Stage 2 components I cranked the ABC pretty far open, so I cranked it closed about 3 more turns. Any suggestions for how many cranks it would need to be open the ABC from all the way closed for Stage 4? I was worried that since it was a used Turbo, there was something wrong with it. I'm running the generic TurboXS Stage 4 map, waiting for my Dyno tune appointment on the 17th of July. The thing that scares me the most is watching the Boost Guage fluctuating so much at the high boost. It seems to happen more at >60% Throttle. I'm hoping it's just a map problem that will get fixed when it gets tuned.
Too bad, I can't just teleport to my Grandma's house, she lives in Greensboro and have you take a look.
256 WHP on Mustang dyno that measures Stockers at 167.