Sambo,
I ran the cooler thermostat (albeit that is correct they do run them hot for better combustion therefore less for the cat to clean up ) in my LS1 with the standard corvette tune and the older cats and it got through, therefore as long as your cats light off and your engine is running smooth with no misfire you should be fine. Also it helps if Jason doesnt stall your car on the Dyno.... that threw it a bit on the first run.
Believe it or not it more comes down to how well they drive it on the dyno.
To give you an idea, if they short shift in the drive cycle that means less revolutions for the time in the cycle therefore less emissions, so they are supposed to know exactly when to shift, also shift smoothly and not chase the drive cycle.. If they don't it has an adverse effect.
If all else fails Jason likes scotch.
