I think some of the responses is due to the fact it IS an exotic metal & expensive at that! HEY, if you got it & want to spend it, have at it! I just think that in the world of serious Stock Elim. (assuming you're in that group) that perhaps the money could go elsewhere.
For me, that would mean engine development, chassis lightening or even acid-dipping (let's face it, it DOES go on!) I don't think you'll save all that much between titanium & the minimum thickness of alum. you could get away with.
Of course, you could do what I saw once---a guy got some CARDBOARD , spray painted it flat silver & told Tech it was alum. He got away with it! .
If your car is a "price is no object" kind of rig (good for you BTW) I'm SURE you could find other/better ways to go faster. Of course I'm sure some REAL old guys could chime in with their ideas ......