Tunes not fully being applied

I’ve read a couple off hand posts about tunes not being applied properly when downloaded and installed at a later date. Meaning you need to download and install a tune at the same time in order for it to be applied properly to your car.

I’ve searched, and I cannot find anything on this, and cannot find those original posts I saw. Can anyone confirm this? If I’m understanding it right, the vast majority of the tunes I’m running right now are missing some component? What exactly am I being shorted on? If I remove the tune, re download and install it am I good to go?

Just want to make sure I’m getting the most out of the cars I’m running.

http://forums.forza.net/turn10_postsm357644_Tunes-not-loading-correctly.aspx#post_357644
I started it here.