The additional grip strength offered by the minor peaks of the thread is minimal. If you use good quality fasteners, you'll get better holding power by lowering the "H Limit" of the tap to shrink the gap between screw and cut thread. It'll put more emphasis on thread quality and cleanliness, but more than make up for a small increase in drill size.
Tapping Tip - How H-Limits Relate to Class of Fit (Part 2) - GWS Tool Group
But if the threads are still getting pulled out in use, you might seriously consider going with helical inserts from the beginning. It'll do a lot more for thread robustness than just about anything else aside from changing from a cast iron to an alloy steel.
If these threads are commonly failing, using a Helicoil or other brand insert should improve strength and life of the threaded hole. That is why Helicoils were developed in the first place—-not as a repair but as an enhancement to threaded hole in aluminum aircraft engines.