Pretty much anything by Airsoft Surgeon would do it for him...
Airsoft Forums UK
Finius
SimonQuigley
metal slide maybe?
CaptainDumbass
Airsoft surgeon.... xD
CaptainDumbass
Ill tell him =D
M_P
If its a tm I wouldn't do anything to it except maybe a pdi inner barrel. It'll be a 17 or 26, I don't think tm do any others
sp00n
they do a 18c too 
jcheeseright
I personally wouldn't 'upgrade' a marui glock at all. if he *must* do something to it, get a PGC slide and then leave it the heck alone, too much tinkering will let the magic out.
proffrink
Awful advice on the PGC slide I'm afraid 
http://www.airsoftcanada.com/showthread.php?t=140496 - And people who tell you you'll 'let the magic out' have just been buying crap upgrades. Be clever and buy the right stuff and you can make what is already an amazing Glock into something extraordinary. TK Twist barrel over PDI too at a lower FPS: http://www.airsoftatlanta.com/Tanio-Koba-G17-and-P226-wist-Tightbore-Barrel-p/61456.htm - that'll fit all TM Glocks; not just the 17.
http://www.airsoftcanada.com/showthread.php?t=140496 - And people who tell you you'll 'let the magic out' have just been buying crap upgrades. Be clever and buy the right stuff and you can make what is already an amazing Glock into something extraordinary. TK Twist barrel over PDI too at a lower FPS: http://www.airsoftatlanta.com/Tanio-Koba-G17-and-P226-wist-Tightbore-Barrel-p/61456.htm - that'll fit all TM Glocks; not just the 17.
jcheeseright
not sure if sarcasm or not... that link says the PGC is the most drop in friendly...
proffrink
Read the pages; the OP is just a guide. PGC is good because as a set (i.e slider and outer barrel) it works well, but if one wants the best combination then that'd be a Guarder slide with a Shooters Design barrel (which is actually written in the guide)
