I assume you read this thread?
I don't think it's the amount of lift thats the biggest problem with running 37" tires, it's the fact that the tires are going to hit the control arms with the stock wheels at full turn. Theres people running them with just a leveling kit. Even with 35" tires, my passenger side barely hit the control arm, and when it hits, aggresive tread will really let you feel and hear it. I knew then I wanted 0 rubbing.
I also really wanted 37" tires, but in the end I went with 35" tires because I haul a Toyhauler (afraid the gearing was getting too tall), have to load motorcyles in the back sometimes (it's not easy now), My Detroit TrueTrac is actually only rated for up to 33" tires, 35" are much cheaper, more options and the specs were better (E rated, higher PSI for the TPMS and higher speed range), and I had heard lots of stories about rubbing and premature wear related to 37" tires. I'll probably eventually have 37" tires, but for now, the 35" tires made more sense to me in a new truck. It seems to me that the companies that really take them offroad like BDS, Fabtech tend to favor the 35" set-up (unless it's a 8" longarm kit), where the companies that sell more to the mall crawlers go for the bigger tires. I didn't consider a longarm kit, because I wanted to be able to return to stock if needed, mainly due to the warranty issues.
Typically a 6" kit lifts the rear 4" and shoots for 6" in front. I went with the Rough Country kit From TopGunz so I could get the better Bilstien shocks. It's basically a 6" kit (4" lift block in the rear) but new springs in the front lift it 5" to keep about 1/2 of the stock rake. I prefer a little rake, so when I pull a trailer or load up crap in the back, it doesn't look like a stink-bug going down the road. And I just don't like the Baja style high front end look. The Fabtech kit is on the other end of the spectrum, it rasises the front the most. If you really want it high, do like Shmits and use diesel springs in front.
Rancho sells a 4" lift (2" in back, 4" in front) that claims to fit 37" tires. 4wheelparts store told me they installed some, and they rub badely, they actuall said they would only use 35" tires on that kit.
ProComp sells a 6" lift for it, but they use a spacer in front rather than a new spring, and I didn't like that.
Skyjacker and Superlift also sells popular kits for this P/U. If you are replacing the wheels, then you can easily get some with less backspacing to avoid hitting control arms, but the wheels will start sticking out more, and won't tuck into the fenders if you put a serious load on just one wheel. If your going that route (or 13.5" or wider tires) I'd get a full 6" kit, maybe even a 8" kit.
As far as performance goes, everything I've read makes the CAI systems sound like a waste of money. I replaced the Y-pipe and muffler, although I now wish I'd have gone with a smaller 18" Magnaflow muffler. Programmers are comming, but are not out yet. I'm still learning about these things, and there are lots of others here that know a lot more than me.