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A lot of preferred vendors on this forums to get your parts from. A tuner is where you will see the most gains.
As one poster already said, your stock CAI is already pretty decent. I don't see where you would actually gain much by way of noticable power, if any at all, by upgrading your CAI unless it would pull in cold air from the fender well, which your stock intake already does. Just drop in a high flow air filter during your routine maintenance. You'd get just as much out of that as you would by upgrading to an aftermarket CAI. The TB spacer, definitely no. Actually, just a couple of bolt ons by themselves aren't going to give you any real noticeable power unless you start adding more bolt ons to compliment the ones you have. For me, I would like to add long tube headers and a Carven muffler to mine. Not that it will add a lot of noticable power but headers and a Carven muffler would definitely improve the tone quality of my 5.7. For immediate gratification I would go with something like a Pedal Commander or Sprint Booster.
All of what you are doing is great from experience 3 inch cat back exhaust (Make sure the Y Pipe is removed), if you want low noise install X muffler if you don't care dual 3 in and out. You could order 3 inch stainless steel system and do-it-your-self.
. They started locking them in 2015 and newer. Longtube headers and better flowing exhaust are good additions. Stall TC will make a big difference, but it'll heat up your 65RFE real quick, so that's the price to pay. Gearing to 4.10 or 4.56 would be really good, noticeable and actually helpful to the drivetrain. But, very expensive if your truck is 4x4. 
