you will need a fuel return line, as the k10 doesnt have one (theres three lines on the k11 -- Feed, Return and Breather)...however theres only a few feet of rubber hose as everything under the car is metal pipe...which you can buy from most places in coils and cut to length.
Tbh id be tempted to lean towards fitting a race type fuel tank in the boot...if it turns out the k10 or k11 one will give you problems.
Theres a K11 schematic about somewhere, for NATS and Non Nats ecu's which should help you out...ive got it on my comp at home, but it should be on the net aswell...dunno if its on here or not though. 
