About 420-430whp sounds about right. Could you do a pull in 3rd? I'm curious to see where your torque peak would end up.
No doubt you have some nice spool from the TMIC, small header and hot side, but I think those will be quite a bit of restriction it you try to push it much more. You will run into MBT much earlier from the increased back pressure.
This would be better compared to the GTX3071 we built a while back that did 440whp on a TMIC at about 25psi. That car hit peak torque at 4k RPM in 4th gear on the dyno (07+ gearing).