Is the jet funnel EOM ?, and what about the mags? Are they extentions of the factory mag or a new mag? I'm thinking of getting an USP40 and setting it up. Is the setup differant for the full size and compact? Is this a factory model?  Is the USP LEM avaiible from HK with the funnell and mags?  

Check out www.hkpro.com, alot of your answers can be found over there.

As said, check out HKPRO.  In short, Jet Funnels are OEM that are used on the 9mm and .40 cal full size in Europe.  They can only be used with the 9mm 18 round and 40 cal 16 round "white" mags.  Ten round and normal full caps will not work with the JF installed.  The JF is not easily used with .45 USPs.  They go on, but no mags fit and mods are required to both the gun and the floorplate of the mags, such as mag extensions.  JF do not fit the P2K or the USPC.

I love mine on my .40 USP Expert