Generators
Linking 2 EU2000 together will give you 4000 watts (33 amps) maximum and 3200 watts (26.7 amps) rated output. Generally you will want to keep it at or below rated output at least 90% of the time.
For pictures, see
http://www.mayberrys.com/honda/generator/accessories/parallel-rv/rv30a.htm
There are 3 sources of the synch cords:
1) Honda dealer (expensive, may require an adapter to use, and with a potential safety problem). For instance, Mayberrys has the original one (needs an adapter) or one with a 30 amp RV socket for $275. Whether the 30 amp one is from Honda or made by someone else, I don't know. The safety problem is that it is possible to hook them up with 'reversed' polarities, which can lead to dangerous conditions if you use any of the regular outlets on the generators. To overcome this, label the leads for polarity, and hook them up the same way every time.
2) 'Aftermarket' dealer (cheaper, maybe $175, but who knows what you are getting) For instance,
http://www.southwestfastener.com/productsHonda.htm
3) Make one yourself for around $50 or less. The one shown here overcomes the reversed polarity problem of the Honda box by using polarized plugs. Also puts the power output on the protected side of the internal breakers. Although it takes more force to pull out one of these plugs than the banana plugs that Honda uses, if one does come out, it will be 'live' and unshrouded (at least the Honda plugs are shrouded so it is harder to come in contact with a live plug). I also note that there appears not to be any mechanical protection keeping the cords into the receptical box except for the screw attachment to the socket. OK if you treat it very gently, but could be a problem in the real world...
http://www.picturetrail.com/gallery/view?p=999&gid=848900&uid=558963