A question for you turbo heads out there!

[Jamesyboy]

As some of you know, the se2 is phase 2, I was given some information that on phase 2 the turbo should overboost to 19psi, and hold at 14 after, now I'm only getting 14 overboost, and holding 12.... So last week I had a tinker and I gradually did some test runs tweak by tweak to be safe, to find the car actually ran worse, so I've brought it back down again, now it hits 15 and holds at 13psi, but the turbo makes flustery kinda noises on full throttle, and kinda holds back a bit, anyone have any ideas why? I was advised by Steve to get new plugs in it, I've got some more here just haven't found the right sparkplug tool to fit them yet, could this be a cause?

[v6 steve]

yes