a lot of similar threads have been posted before but those threads are well buried by now so what the hey...
this is the only seriously modded gun i have as far as externals go, it started life as a Tokyo Marui MP5K but because i no longer need such a compact AEG so i modded it into a CQB assault rifle. (about 350FPS)
added the M4 style tactical crane stock, scope mount for scope+laser, extended 6.03 tight bore barrel and silencer outer barrel extender. hand painted the hot rod style flames on the silencer and used stencils and spray paint for the skull graphics on the body and scope covers.
before...

after...

__________________
Lead me, follow me or get out of the way...
(Major General George Patton)
note to self: next time you find yourself staring into the fiery pit of hell, just remember, tap twice, zip up your fly and walk away...
blog link:
http://www.airsoftsociety.com/blogs/viewblog.php?userid=500