Trainers by their nature are trimmed out to fly level at one speed. When trimmed out this way, they lift the nose when in a dive due to excess speed, as well as lower the nose when left in a climb and slowing down. It suppose to make them easy to fly for the rank beginner. The airfoil used by trainers is a small part of the reason, but not really the primary reason.

This "self recovery" mode of operation is driven mostly by the decalage and the balance of the model. The incidence of the wing relative to the thrust line, and the angle of the horizontal stabilizer determine the decalage. Having the airplane balanced out "nose heavy" is the other factor that increases the effect that speed has on climbing.

Most trainers have a fairly wide band of permissible CG ranges. You will dramatically improve your pitch/speed problem by moving the CG to the rear of the range. On some designs, even operate slightly behind the "approved" range. Then removing much of the excess decalage will give the result you are seeking.

Other things you can do if you find your trainer too tame. Cut down the wing area by one rib in both panels will increase the wing loading and speed. I've done that to an LT-40 in the past.

I've also remodeled the airfoil of a Goldberg Eagle 63, making ribs that glued to the bottom of the wing to make a semi-symmetrical airfoil. Just remove the covering on the bottom, and glue them on beside the existing ribs (about half the camber of the upper surface).

Or you can replace the wing entirely with a wing from another airplane. I put a 400 square inch symmetrical wing from a das little Stick on a Eagle 63. Interesting test flight ensued, since I didn't remove enough of the down thrust.

Any questions?