Pre'Race Gel Packs

Good Morning! My son is a 13 yo age grouper that has amped up his level of competition this year. In addition to driving and writing checks I am helping him sort out his nutrition. Has anyone used the Gel Packs prerace. I use them for my own exercise and find them quite helpful at times. If any of you have any experience with them on race day I am interested to hear your results. Any other advice about prerace food strategies would be appreciated. We have also changed our diet daily to handle his increased caloric needs and it is working out pretty well. Regards Spudfin