First let me get this out of the way, if you think CAI's are stupid and useless great, but please don't post here. The main reason I'm making this thread is because I was fortunate enough to be able to try a volant and an afe stage 2 si back to back. I bought a volant used for a decent price and then my neighbor wrecked his tacoma and just gave me his afe (I did end up giving him $100 plus my lawn mower). I drove about 400 miles with the volant ( 2 tanks of gas), put the factory intake back on and drove another 1 and 1/2 tanks with that and finally I have the afe on right now and have gone only 1/2 a tank with it.
The volant was nice, it sounds good and there is a definite bump in power on the highway. Around town it's no louder than stock, and it was close to stock in mileage. The LTFT was higher than stock though and it did decrease mileage by 1-2 mpg's with an overall mile reduction of maybe 30 miles per tank. If you really wanted the full benefit with this I'd say get the ram air scoop and the urd calibration unit, then you'd get the mileage back and probably have even better power.
With tHe stock back on after the volant the throttle felt lazy, like it had to think about things a bit before it did anything. Passing on the highway especially felt a little harder but the mpg's did increase. I have to admit I did miss the intake sound a little.
Now the afe, if I was going to bu a new intake I'd go with this over the volant and anything else I've seen. I haven't driven it enough to give y'all a mileage report yet, but the throttle response is just as good as the volant if not better, and its much better than stock. It's better made, with a post for the engine cover and a better platform for the MAF sensor to sit on. The volant doesn't seal as well and also doesn't allow for the engine cover to be attachd at both sides. Also, the air seems like its funneled better, with a gradual cone until it gets to the throttle body, the volant is just a straight tube from filter to throttle.
Volume with both was fine, neither was obnoxious IMO but that's a personal thing. I somehow deleted my volant pictures and yu all know what the stock looks like, but here are a couple of afe pics. If you can find a sale on this I'd say its worth it but I don't think I'd pay the full $350+ price I've seen on a lot of websites. Somebody said that auto anything has a sale on these right now, and there is also afe intake.com if you think you want to buy one. The volant is less expensive but if you add in the urd calibrate unit it ends up being more expensive.
Finally, if you have a 1st gen TRD intake the afe is nearly the exact same thing. I say nearly because the air box on the trd has only 1 air inlet, but the afe has an optional front intake section that yu can seal with a rubber plug. I've been driving with the plug removed and the intake temp is still a little lower or equal to stock, around 5 degrees higher than ambient. I plan on testing it with the plug in after a couple tanks to compare.