Technically I guess you can say that the 6.0 can stack tuners. Your able to use a tuner of your choice to program the PCM/TCM, and then use the Gryphon FICM tuner to program the FICM.
This in NOT the remote FICM programmer that you get as a "loaner" and return back to PHP. This is the Gryphon non-CS/CTS that you can buy that has 4 levels of FICM tuning that you can swap FICM tunes as much as you like. Cost is $399.
The Gryphon FICM tuner from PHP comes pre-loaded with 4 FICM tunes. You get to choose any of the four. Economy, Atlas 40, Atlas 80 and Hercules. Install was pretty straight forward.
Remove FICM relay, cycle key to on, plug in Gryphon to OBDII, follow the on screen instructions (push some buttons and some on/off key cycles), re-install FICM relay. For the first install, it took about 5 minutes from removal of relay to re-installing relay.
Currently I'm running the SCT with SRL++ written for the older/less desirable strategy (VXAP2). So the first FICM tune I loaded up was the Atlas 80. Throttle response was much better while pulling out from idle to easy accelerating, with no smoke.
Cruising down the road, and applying heavy throttle, you can feel a smoother motor, and seat of pants power bump. No smoke.
Cruising down the road and slamming the throttle to WOT, she pulls harder with the Atlas 80 combined with the SRL++. Power increase can be felt by the seat of the pants. Smoke is a different story, running the SRL++ without the Gryphon there is very little smoke, just a light puff then clears up. When running the SRL++ and Atlas 80 while slamming to WOT, the puff of smoke bellows out then cleans up to a light haze.
So next I decided to turn on the water/meth, currently I'm using washer fluid (70/30). I have the settings to come on at 13psi boost, then by 23psi boost its injecting 100%. Cruising down the road and laying on the throttle steady, power was smooth and noticeable, no smoke. Cruising down the road and slamming to WOT, the initial puff of smoke was alot, then cleared up to no smoke, not even a haze.
For those of you who run the SRL tunes, you know what I mean when I say that the SRL tunes are very clean (almost no smoke at all).
I'm very impressed with FICM tuning so far. The nice thing is, the SCT tunes combined with the FICM tunes will give me multiple power combinations. I wish I had the time to try all my SCT tunes combined with the Gryphon FICM programmer, but with a total of 36 SCT tunes (new/old tunes and canned) and the option of 4 FICM tunes it will take me a long time. As time goes on, I'll try different combination.
With camping season right around the corner, I'll be able to use one of my tow tunes combines with the Atlas 40.