Okay, i'll divulge the "Secrets to getting your son to 90+mph"
PBJ, Oatmeal, Chicken Tenders, All meat covered in BBQ Sauce, waffle sandwiches (2 legos with butter) and mashed potatoes and leisure peas.
Seriously, i did consider a weighted ball program once thru an instructor near Atlanta. I talked with him and we never went down that path. I think it works and players see gains....im not sure how much is retained over time?