Jay, that was my thought as well, it's for swirl. The TFS have a lot going on that's unfamiliar to me, the vane in the floor being most prominent but the floor is also slanted quite heavily, and then the ramp on the roof as mentioned.
The easy first question is if this ramp somehow helps with lower lift flow/atomization but is part of the reason they start getting noisy at .600" as several guys have reported? As the assumption is these heads were aimed squarely at the hydraulic roller street guys, it jives that they'd maximize them up to .600". I did my best to check the minimum CSA and came up with 2.56sqin, which according to the calculators, jives well with a 6000rpm 445-462 deal, or a 7000rpm 390....which is also .600" and below cam territory. The throat came in a 90% of the 2.19" valve, which I understand is fairly standard, with "race" stuff pushing a bit higher with steeper seat angles for high lift.