depends on what type of car and what you do.

if you drive a civic and altezza, and ur in ur 20's ur too old for that.

if you drive an NSX with some deep dish, chrome 20's and a twin turbo, never too old for that.

apc stuff 20 and under
full body kits - 23 and under
lips and add-on kits - never to old
turbo - never too old
etc.