Originally Posted by shears
I have an S&B and i didn't notice any MPG gain, but I firmly believe that CAI don't really do much for MPG (definitely won't make it worse though). But some people do claim that their MPG does slightly go up. It did make the exhaust tone a little deeper.
Mod your exhaust. You don't have to do anything crazy, just remove the resonators and change out the muffler. I went with a Flowmaster Super 10, Really loud when you stomp on it and quiet when MDS kicks in. That's all you really need to do if you just want a better sound to your truck. Lifted trucks without a deep growl are silly to me.
I would go with 4.10's.
Answer to your question on which to do first.... It all depends on your wallet, but all except the throttle body spacer should be done.
For anyone running 35's and wanting to do a gear swap, I also recommend 4.10's for daily driving but 4.56 is surely fun on 35's