Depends. I bought a new pair of Salomon Xwave 10 boots a few years ago and had a new pair of footbeds made for them. After about a dozen days, the Salomons packed out too much, and I ended up selling them. I took the footbeds out, and put them in my new boots, a pair of Head World Cup boots. I went off to Steamboat for four days of skiing, and suffered like I never have before. The last of the Heads was much narrower than the Salomons, and the footbeds just curled up around the edges. Even after having the footbeds modified a couple of times, they were never right. Oddly enough, I ended up taking a pair of custom made footbeds out of an old pair of Tecnica Explosion boots that had been lying around in my cellar, and they fit like a glove. Have had them in there ever since. So I guess it all just depends on the boots themselves. From my experience, some boots you can do it with, and some you can't.