@Brad -
I just got the Gonkulator on this. Dragstrip testing of the BBM heads so I was very interested.
Here is what the Gonkulator got with your 4200 stall, after I matched the 60ft which didn't take long:
Torq 579 at 4200
Powr 545 at 5700
1.48-6.82 at 100.0
With a 5000 stall
1.46-6.74 at 100.7
I didn't think it would care since 4200 is already peak torq, but it does seem to care at least in the Gonk. This is still with the RPM intake.
I tried shifting the Gonk at 6400 vs 6200, no difference. Save the revs!
I don't have a lot of Gonk experience with the Yates intake but I just made my best 1st guesses based on the A3 intake so here goes the Gonk
Torq 573 at 440 -6
Powr 566 at 6100 +21 and +400rpm
1.48-6.80 at 100.6 .02 and 0.6mph gain
Then with 5000stall
1.46-6.71 at 101.4
1.46-6.70 at 101.4 shifting 6400, gains .04 sec and 0.7mph vs Ed RPM intake
The old "10 ponies = 0.1 sec = 1 mph" rule doesn't apply here, but I find if you use that rule PERCENT wise, it is still pretty good.
That rule was meant for an engine making about 300 ghp or 250nhp, and you're making near double that. So it figures, you need about 20 ponies gain to get that same effect. Since you only added about 7 ponies (average of -6 torq and +21 hp) but added 21hp, the gain will be somewhat shy of that 0.1 sec and 1.0mph. So it makes sense. As you know better than I, its hard to make a car go faster when it's already high-10s in the quarter equivalent.
For fun I ran the car "fully hooked", which is slightly easier to do in the Gonkulator
1.41-6.63 at 101.6
So I suspect that with the 5000 stall, traction is going to be the rest of the game.