I recommend not doing a CAI or the exhaust. The cost of these mods will outweigh the minimal gain (if any) that the mods bring. It is obviously dependent upon your specific situation. If you drive the truck a million miles, then maybe you make your money back. Maybe. (not a real number btw).
I would buy a tuner, and call it a day. Even the tuner is on the line as far as the cost vs savings are concerned. Its a bunch of math, but it comes out being smarter to just deal with getting less mpg. A good example is that i have every possible bolt on mod and still get the same mpg i did before. (worse actually). That won't always be the case, but my point is that mods do not guarantee additional mpg. Paying for these mods absolutely = an immediately loss of money. (cost of the mod) So even if you decided to do the math, and the fact that you plan to drive the truck X amount of miles (a whole, whole bunch) shows that it would be worth X amount of money (cost of whatever mods you plan to do to gain mpg) to do the mods, there is still no guarantee that the mods will actually help you gain these mpgs. And even if the mpgs do increase, how much will they increase? 1? 2? 3? And if they actually did, then how long would it ale just to pay back the 1000s of dollars spent modding? So really you would just be gambling, hoping that the money you spent to try and save money will end up actually doing so. If you want to do modding for fun, then rock and roll. But for the sake of milage, its a no win.
Someone posted it here on a thread a while back, but i will quote them loosely here... ''The best mod for additional mpgs is a light right foot.''
Just drive smarter and get the best you can. Leave the rest in the cash register at the gas station.