Hey Marko,
If you're talking about Academy's new 1/48 scale CH-53E kit, then no. There are no detail kits for that kit that I know about. I'd imagine that the first detail kits for that model start coming out in the next 3 months or so. However, I've seen aftermarket kits and accessories for Revell of Germany's 1/48 CH-53G.
I'm not much of a scratch builder, but a few simple little modifications/fabrications can add alot of detail to the model. I have a thread on this forum going which illustrates a few of the modifications I've done to Academy's kit. Here's the link.
http://www.finescale.com/FSM/CS/forums/640840/ShowPost.aspx
You can also check out my photobucket page for CH-53E reference pics, and more pictures of the work I've done on Academy's kit.
http://smg.photobucket.com/albums/v491/ridleusmc/
Good luck and Happy Modeling,
Semper Fi,
Chris