But the Evo has a 61/39 torque split. It is mostly FWD...
That's a bit incomplete and misleading. Here's some information straight from Mitsubishi that is a nice technical read:
http://www.evoxforums.com/forums/showpost.php?p=210643&postcount=1
There is so much more to handling dynamics in an AWD car than just raw torque split. As you know, Haldex
is FWD in default mode. ACD in the Evo is full time AWD but will vary to 50:50. The STI is a bit more rear torque biased than the Evo, but still has substantially more understeer and doesn't handle anywhere nearly as well.
When coupled with SAYC, there is no need for more than 50% of the torque to go to the rear wheels. The yaw control will cause the car to throttle-on rotate like a rear wheel drive car, sending torque to the outside rear wheel. It's loads of fun, if not a bit unnatural at first. I spun my Evo X a couple times when I was getting used to it on dry tarmac.
It's not my intention to belittle the R, but even with a stability control disabled and a Haldex controller installed, it's nowhere near the league of an Evo in the handling department. Some of the cost of the R goes into comfort, whereas the Evo is a focused track tool. The Evo has a much stiffer chassis, better suspension, active yaw control, wider and more aggressive tires, and substantially better brakes.
On the power side of things, the Evo's advantage continues. It has a larger turbocharger than the K04, more tuning options, and an engine that can safely rev 1000rpm deeper than the FSI.