Sorry--that last statement was an addition to my original post, and I thought I was on SDs Procharger thread.....
And that torque number is really low for N20.
So, that begs the question---what was your bottle pressure? I am just asking as when I had my car dyno'd 3 years ago on nitrous, I gained 34 rwhp by raising the pressure from 900 to 1050 with no other changes. I know in the instructions Zex recommends 950 psi but after that I always ran 1000---not sure what your kit recommends, but whatever that number is, did you verify you had that pressure?