Wish I had access to a dyno - Volant ROCKS!
After putting 5200 or so miles on my '07 XL Denali, I installed my Volant intake kit today. This is the first powertrain mod I've made. A trip around town and on the highway after the installation yielded surprising improvement over the stock setup. While it's obviously still to early to tell re: fuel economy (main reason I went with this), the performance boost is pretty sweet. You will definitely hear a difference in the throatiness of the engine. In fact, I can even "feel" it in the throttle. The difference in power at mid-range RPMs is pretty obvious too. While I probably will never know for sure, I'd like to think I'm at 400HP at least, and around 435 lb/ft torque or more, but I can't say (it just sounds cool I guess - hehe).
Installation wasn't too bad, but since I've never done anything like this before, I took it slowly. Volant's "instructions" kind of blow; even though it wasn't too hard to figure out. The most surprising thing to me is the huge difference in size and shape between the stock air box and tubing, to the point I first thought there was no way I had the right parts. The stock intake tubing "assembly" has two large "lobes" on it: one is on the lower part of the tubing near the breather hose connector and is rather bulbous looking; and the other runs mostly parallel to the crankshaft and sits atop the engine block under the composite "Vortec" cover (which must be the resonator to quiet things down). You will have to remove the "accessory plate" on which the stock airbox sits, and the Volant intake box bolt holes line up perfectly. The breather hose is 8" long - wouldda been nice to get another inch so we're not tugging on it so hard at each end. Anyway, no issues with the installation, even for a total newb like me it took only 'bout 45 minutes. Volant does not offer the lower front fascia scoop option for the 6.2, and I'm scared to scoop up water or other road crap anyway the more I think about it... I'll check things out in a few days to make sure it's all still nice and snug.
I'll post a follow-up in a week or two to update my fuel economy, if I can resist keeping my foot outta her! Currently at 10.7mpg, and I hope to see things improve a bit on the next tank of Shell V-Power (Mobil-1 oil change was last weekend).
Next up: a programmer! (Well, after my McCulloch HID kit.)