I have the 63 series CAI from K&N and I've been pretty happy with it. Don't expect to see considerable performance gains, but I did feel a slight increase in power during "high speed" accelerations. The whole idea behind a CAI is to bring in more, cooler air to increase engine efficiency. It would probably be best if you paired one with a full exhaust system, that way you are bringing the air in and blowing it out in a more efficient manner. The CAI most noticeably made my exhaust sound a little better…but as far as noticeable performance, it just depends on what you consider to be noticeable. With that being said, if I were to buy a new truck I'd throw one on…I don't really have a justifiable reason for you, I'm just saying I'd do it again. I wouldn't bother with a throttle body spacer…all it will do is make a "woosh" sound. To quote JennaBear from BlackBear performance tuning: "The TBS are a waste on the newer engines as the fuel is sprayed after the throttle body. The air is already "spun up" as it goes through the throttle body, so the TBS basically duplicates the effort. The TBS won't hurt your engine however, that being said, some folks wind up having problems with the spacer as it is one more thing to wiggle lose and cause leaks." That pretty much sums it up. I also bring up BlackBear because for myself I intend do use these guys this summer rather than a "chip", "programmer", or "tuner". BlackBear logs data and makes changes specifically for your truck and driving application, whereas a tuner can only take you as far as the tuner will let you. As far as the 2014 models go, I definitely would not be willing to put a tuner on one. Because of the new technological advances I would be hesitant to do any engine work besides an intake and exhaust until about a year or so. The bugs have to be worked out and these trucks keep getting smarter and smarter -- a guy that works at my dad's dealership has a 08' Duramax that he installed an H&S tuner on (which is a pretty popular and "respectable" tuner), and it no longer works because the trucks computer system "figured it out" and shuts it down while in the "wild" setting. All of the work was done by our award winning service dept, so when even they suggest that I (being the owners son, not just a customer), stay away from tuners, I believe them. Bottom line if it was for me, start out small with these new models and eventually work your way up! No Tuner, no TBS. Hope this helped! PS if you do decide to go with a CAI, I got mine from autoanything.com -- that is what I would recommend. They are always running 20% off promotions that are applicable to the K&N intake that I got…so it isn't such a "waste of money".