Cummins ISM not reading boost correctly?

[in2trux]

Well, I'm out of ideas except one. You need to adjust your driving style. It's just not going to pull like a big bore, Cat or Cummins. Try working it tighter, 1400- 1700 rpm, leaning toward the high side. 60 k with an Ism is like 80k with a big bore.

Ism is pushing it's limits at 60k. 30 psi of boost is as far as we take our Isx, 38 is max and is rarely pushed that far.
Whats the rest of the driveline like? 3.73 rears / 10 spd, 75 mph would be best it's going to do.