The '09 and '10 R/T's 5.7L HEMI is what is known as an "Eagle" engine. "Eagle" is the development name used by Chrysler Engineering for the most modern version of the HEMI. This newer version has Variable Cam Timing (VCT), among other features, that distinguish it from the older, non-VCT HEMI architecture...which includes all earlier 5.7s and all '08 through '10 6.1L SRT engines. I bring up this distinction between the older 5.7s/6.1s and the newer '09+ Eagle 5.7s because the Mopar all-aluminum genIII 426 crate engine of which you speak is not an Eagle; it is essentially a larger version of the SRT 6.1L with an aluminum block. While it's a killer-sweet piece for sure, it will be a tough, PITA swap into your '10 R/T because of your car's newer Eagle engine controller. I feel your pain in this: I want that aluminum 426 real bad, but I have an '09 R/T, so I'm in the same boat as you. I'm now trying to decide whether or not to trade my '09 R/T for an '09 or '10 SRT so I can just swap in the 426, which is directly compatible with the '08 through '10 SRT engine controller. Or, there's another, simpler, route for us to take: the new '11+ SRT 392 HEMI just happens to be an Eagle. Since it has VCT, etc., it is apparently completely compatible with our engine controllers and tuning of it will be a relative snap. This is rather cool since, as of this date, tuning of the '11+ super-secure controllers is giving everyone fits. It seems that, right now, the only way to tune a 392 Eagle (without shipping the controller to a third party) is to install it into an '09 or '10 R/T! How cool is that? The 392 may not have an aluminum block, but it is a huge leap in performance over our 5.7s...and it's going to be seeing a lot of future development. Hell, they're already claiming that it's easily expanded to a 426 (or more), so if you don't mind the screwing around with rebuilding...there's your 426 anyway. Just food for thought...
Regarding Arrington, they have a great reputation as they're a major builder of racing engines. They do know their stuff.
Last edited by 1analguy; 01-25-2012 at 07:28 AM.