I found that when I installed my 1 7/8" ARH headers w/3" ORY on my truck ('08 AWD Sierra Denali - White, just like BuyAmerican's), the mixture was way rich too. I was getting a WOT AFR in the low 11s to high tens on the LM-2.
Turns out it was because the mixture went way lean when the headers were installed and the ECM over compensated by way of the fuel trims and was dumping lots of fuel into the engine. We've done a "quick and dirty" re-tune so far and it runs at about 12.6AFR @ WOT now. I've also noticed when I log a run that max timing is only at like 21 degrees at higher rpms, so I need to play with that. But, it runs much better now than before the retune.
I ran it on a G-tech the other day and it ran a 8.83 @ 79.5mph in the 1/8. Besides the headers I have a Yank PT 3200 and a Vararam ram air intake and a ported TB. I also have a Zex 125 kit on it too, but the time above was off the spray. Best time on the spray so far is a 8.36 at 86 mph (before headers, stall and Vararam), spinning all four tires through all of first gear. Not bad, I think, for a 5500+ lb. vehicle (w/ me in it) w/ factory 20's. I think I can probably put it in the high 7's, if I can get some traction.

 

Could you tell a big difference when you put the Vararam intake on it?

 

I did. It was a noticeable SOTP increase in power w/out tuning, but I never ran it back to back against the Volant CAI which I had on the truck previously. I think my truck was running so rich that the VR really helped the lean out A/F mixture and that's the reason why it works so good.
I have to say though, that although the VaraRam works and appears to be decent design, the workmanship and materials leave a lot to be desired. The flex hose they use to connect the ram air snorkels should be smooth molded plastic, IMHO, and the air box front cover seems to be distorted (bulging)because it has three small screws - one on each corner- to hold the front cover on and it, flexs in between the screws. It's also a bit of a PITA to install, and to clean the filter.Also, there are no instructons as to how you connect the PCV valve hose to the VR. The instructuions seem to indicate that you have to connect it to the short 4" hose between the MAF and the throttle body, but there is no connector to do this. For now, I have my PCV plugged. Also, both threaded inserts in the snorkels wrung out of the plastic when I tried to tighten the bolts, so I had to use small stainless bolts and nuts w/ fender washers in their place.
I might take the Volant to the track one day and test the two back to back just to see the difference. When I do, I'll post the results.