most mods come when A) they are cheaper than replacements, B) you want more HP/TQ, or C) you have no other choice. there is really no SET time to buy these things, just when your little SC heart desires.
Anyway, an 80mm MAF and anything bigger than a 75mm TB is really over kill if you don't have a seriously modded motor. I would say go with 76mm MAF and a 70mm TB. You can get both at SCP. Here you go :