My dad has got 2 or 3 of these and i asked him about them.he reckons theyre comfortable for about 80 miles or so,the riding position is good but the seat is hard.he says they are reliable and to run them on a semi synth oil as the clutches dont always like a fully synth and can make them slip.the 3tj is the grey import model and the 4dx is the uk spec model but they are more or less exactly the same bar a few minor details.spares are very cheap second hand and fowlers and granbys still carry a good stock of stuff for them.try the 400 grey bike forum as it has a section just for the the fzr400 and they are very helpfull.the 3tj model is restricted to 112mph and needs an mph converter to unleash the last few mph,it fits on the back of the speedo as thats where the restriction is but he says its probably already been done if its been in the country for a few years-any thing else just ask