first of all, every boot in the ski universe is made with a plug; little kid's ,women's, men's, rental to world cup. the plug is simply the inner mold that gives every boot it's "inside" shape and determines volume.
daron and giorgio and others sometimes use a foam liner depending on snow conditions which employs a lace up liner (atomic made). the race boots are EXACTLY the same as the Ti, the only difference is that they have 3,5 or 7 mm's of lift inmolded (also available in the u.s. from the racing dept).
the boots use polyether just like the boots you can buy. there are (at the elite levels) cuffs and lowers available in flexes that are in between what is offered here in the states for example...selling four flexes to the public is hard enough, imagine if we offered all twelve!!!! the vip is the race room version of the production tri-tech boots and is still favored by a few for speed events only.
much to the dismay of many people...there is no top-secret, silver bullet out there. obviously elite level athletes are always testing new and different ski or boot combinations/constructions/materials, and are always 6-10 months ahead in terms of what you can buy but.... at the end of the day the boots are all still plastic and the skis, wood and metal.
atomic racing dept.