The BMW guards are cost effective and very easily installed. But in my experience they are a single use item, more or less. In a minor incident they will self destruct and save your levers. Much more than minor and bent levers will happen along with destroying guard. They do work well with the stock bars in that they bend very easily as well. If you just want the “look” and “just in case” and not intending much off track use the BMW units are swell. If you decide to go more robust, there’s many brands of sturdy aluminum guards. One hot tip I learned was to get threaded inserts to mount the ends of guards on handlebars. Such a better way to mount and no coming loose. If your changing your bars (and you should) to fat bars the “Highway Dirt Bikes” brand is pretty superior gaurd and incorporates a nifty folding mirror much superior to the common used ones.
if just wanting wind protection the MX style guard might be dandy and even easier to install than the BMW, no cutting on either though, last I looked the BMW one was a bargain.