The 2wd and 4wd inlet are slightly different, the 2wd has a elbow that is seperate to the plenum cover, the 4wd is 1 piece, and ever so slightly better so people say.
The L8 has more potential, for add on bits, if you are on a L6, ie 2wd sapphire then there won't be any real difference unless you want the toys AL/LC/CL that can be added to a L8, if you are on a L1, ie 3 door cossie ecu then L8 would be a better bet as would a L6.
To go with the L8 you would need to TPS, and need to swap the outer two wires around if on a 2wd wiring loom.
The tps can be bought for about £45 by using the 100% exact same sensor fitted to certain ducati motorbikes.
tabetha