Luke pretty well covered it. The Tikka is a trim gun to begin with, so you don't have much to improve on.
The barrel lends itself to fluting (long, straight taper), and that might net you 6-7 oz of wt loss. The factory stock is pretty light already (mine is 28 oz) so the best you can get from a Manners or McM Edge is maybe 4 oz at best. If you really want to shell out the cash, you might do slightly better with a MPI carbon fiber stock, but I haven't heard of anyone that's tried one of those. I'm not aware of any currently produced Ti bolt handles, but the factory knob is already extremely trim and drilled out so that wouldn't net you anything measurable. Even so, fluting and possibly a slightly lighter stock will get you well under 6 lbs, which is probably all the further you really want to go with a magnum gun.
Leupold scopes are usually the lightest thing going if you want to get that picky. Stick with a 40mm objective to keep it lighter.
My personal Tikka is as factory issued and mounted with a "heavy" Zeiss Conquest 3-9x40 on it. Thus far I've managed to drag it up the mountain ok, but when get around to modifying it it I'll buy a decent stock first. Not really for the weight savings, but because I like the feel of a high quality composite vs the relatively slick plastic.
Yk