this a trick my old race coach taught me a few years ago that i have done for my last 3 pairs of boots and had great results. basically what it does is help make the footbeds mold to your feet, which significantly increases the comfort and performance of your boots. i promise this is legit advise, not some bullshit that all these ^ kids like to say because they think its funny.
what you need
-2 small oranges (not clementines)
-2 large oranges
-2 bottles of water
1. boil water in a medium saucepan. once the water is at a nice roll, put the oranges in the water whole, with the skin ON.
2. after 5-6 minutes of boiling, remove the oranges with tongs and place them directly inside your ski boots, the small one at the toe of the ski boot and the large one in the heel. the steam from these oranges helps to relax the foam slightly, which then allows a citrus chemical to temporarily change the some of the chemicals which compose the footbed into a more aqueous solution until the water starts to dry out and it becomes rigid again.
3. place bottles of water in the ankles of the boots. they should fit fairly tightly, although it doesnt need to be sealed. this keeps the reaction from step 2 in the footbeds and prevents it from effecting different kinds of foam present only in the ankles of the boots. it also plugs the holes so the steam doesnt get out.
4. after 15 minutes, remove the bottles and oranges from the boots and put the boots on your feet. the longer you can keep them on the better, but keep them on for at least an hour to make this trick work most effectively.
5. to dry the boots, remove the liners and set them out in a warm dry place.