When ordering Killer Planes Crashproofing, "Foam Prep" means we drill all the holes in the foam body, wings, and tail(s) of the airplane. Then we cut all the grooves, pre-cut the rods, and put them in their respective holes and ship the plane. You, then, take out the rods and glue them in according to our detailed gluing instructions. It's the second best value we have- the installed is an even better value, because it works out to about $10 an hour to save yourself the work gluing rods, and wiping off the glue as it expands.
Reinforcement is one of the few things that's actually worth more than it costs -- as soon as you get it. (Immediate return on investment after your first crash) Our customers are way lucky- I had to invent this stuff to get it in my planes, and I destroyed "a few" planes before perfecting it! Save yourself LOADS of dough, and LOADS of time spent repairing planes. Fly it, crash it, and fly it again!