Turbos and timing

[Humble]

This one is aimed at Wally and anyone else running efi and a turbo. What kind of timing/advance are you running and how much boost? I'll be hitting the dyno on Monday but right now my car doesn't want to wind up above 5k under load and I think it timing related. I'm getting about 15 psi boost pretty easily but it just hits a wall at 5k and I back out of it because I think I'm hearing detonation. I've got 34* by 3k off boost, and as soon as I get 3psi it backs off to 24* and down to 20* by 15psi. I'm not sure if thats going to far or not far enough. Free revving the engine has no problem and goes all the way up to 7500.