5-7 psi is typical of what that turbo wants to put out, so you have a good working setup there.
. It can push more boost, but 5 psi is about the limit before you really have to dump more fuel in and you need higher RPM as well. Mine tops out at about 10 PSI right now (guessing close to 3000 RPM).
If you think its easy to kick the tires loose now, just wait until it rains. I've got a posi 3.08 rear end and I have to be careful on wet pavement because both tires kick loose even in a strait line. I can't wait till it snows....
Great feeling the first time you get it working. Best thing since sliced bread