Here are a couple of pictures of my 2007 WR450 with the Clarke 3.6 gallon gas tank.
The bike weighs about 260 pounds empty, and made 44hp with stock exhaust.
I use this bike for dualsporting in Michigan - single track trails, ORV, snowmobile trails, gravel roads, and pavement connectors. We typically do 200 mile day rides from base camp, and encounter hill climbs, river crossings, sand whoops, etc. It is hard to find a bike to cover every adventure. My riding buddies have DRZ's, Husky TE610, WR426, KTM300EXC, and CRF450x.
I have done 150 miles before even having to flip to reserve fuel.