No, the cowl isn't being "held down". The problem is that the cowl is too short to fit all the way back to the lip of the fuselage. I don't know how to "massage" fiberglass to stretch it about 1/4". This is a common problem with the TF P-51 ARF. Here is another view of the problem:
http://www.rcuniverse.com/forum/rc-w...l#post11816216
BTW, I'm not the only one with this issue as it's been discussed several times on that thread. I guess when you buy what is supposed to be the "top of the line" ARF brand you shouldn't expect the parts to fit correctly?