You just need to adjust your Pitch and throttle curves. Sounds like your throttle might be set too low under your pitch. I always set my throttle curves a slight higher than the pitch to compenstate for the extra load on the head at higher pitch angles. I don't think you need expos. Straight curves should do just fine.
Normal mode: 0 @ low point , 55@ middle point, 90@ high point for throttle.
For pitch, try -2 degrees @ low stick, 0@ middle stick, and +9 to + 11 degrees at high stick.
Stunt modes should be 100@ low point, 50 at middle point, and 100@ high point for the throttle. For your stunt modes, all you need to do is adjust your middle point up from (50-80 for Nitros and 50-95 for e helis) depending on how much power your engine is giving you and your flying expectations.
Pitch should be -11 to -14 degrees at low stick, 0 @ mid stick, and +11 to +14 degrees @ high stick. Just make sure your max - and your max + value match. So, if you have -12 at low stick, then you should have +12 at high stick and 0 in the middle. If you get un equal values, take the difference between the two and divide that value in half. That will give your ideal pitch range to shoot for on both sides.
You probably already know all of this, but I'd check your program before you go and start blaming your engine. That fact that two different engines are doing the same thing suggests that the problem is in your head or your program curves. Of course, this is assuming that your engines are healthy and tuned properly.
Another thing you should check is to make sure your pitch is symetrical. Measure the distance between the top of the main bearing and the bottom of the yoke, divide that in half and set the top of the swash plate to the center point. Then adjust the swash links to match. Then, you just need to set the blade grips to 0 degrees by adjusting your pitch links. Center your servos and servo arms with your stick position at exactly center stick. The align head is a great head and adjusts easily. So, once you do this, you should get the same pitch on the + and - side of your pitch range with perfect 0 degrees in the middle. The default throttle and pitch curves should work well after you've done this. You can tweek it to feel just right from that point. This teqnique works well with any traditional style head assembly. Give it a shot and see if it helps you out any.