I put Flatland racing ones on my 01 400E. I got them from Mike Krueger at Cycle Zone KTM ( http://cyclezonektm.com/ ). They're a little thicker than the DeVol's I have on my 99 250E.
They fit perfectly and were relatively easy to install. I used the stock bolts rather than the allen head screws they sent along, though.
BTW, the trick to making the install easy on either of these brands is to go to Sears and get one their 1/4" drive flexible cable-like extensions. Save yourself a lot of aggrevation and get one of these. I use a standard 1/4" drive flexible knuckle type driver to finish off tightening them as the cable driver will not let you crank them down tight enough.