I ordered this from WGC at the same time as my metal slide and various other accessories for my G17. I'd heard that the Guarder recoil spring was the best around and even though the metal slide came with a new recoil spring, I still got the Guarder one, because it wasn't much and it's better.
Well fitting it is pathetically easy... Strip the gun, take out stock recoil spring and rod, replace with Guarder one. Done.
It makes a nice metallic noise, even without a metal slide barrel and it certainly makes the gun crisper and cycle faster.
10/10 because it has no cons and it does exactly what it says on the tin.
Extra pics:
------------------------------
For sale: KSC M9 and mags - PM me
For sale: Kendo Custom Barry Burton M9, very rare - PM me
For sale: A fair amount of brit kit - temperate and dessie!
Look here 
WANTED: Eotech replica, KAC QD silencer, US gear, general AR accies :P
