Baseplate throttle stop for an Alcohol carb Question

[HolcombS/G155G]

I currently have a 565 bbc w/ a 1250 Nickerson 2 circuit Alcohol carb and a dedenbear under carb co2 stop on my 04 Quay XL dragster. I read somewhere that alcohol carb combos should have slotted butterflies in the stop for when the engine is coasting so the fuel doesn't puddle and create a rich condition when it comes off the stop. My carb has 192 jets all around and a belt driven BLP fuel pump. I'm just wondering when the car comes off the stop if its creating a rich condition by opening up and dumping a ton of fuel. I currently run a standard stop w/out slotted butterflies. I don't run the car all out hardly ever but the car will run 176-177 mph and it will only run 169-170 on the stop. It just seems like its losing a lot of mph on the stop. I have a 9" spragless converter from Select set up for this combo and the car weighs 2025 w/ driver. Any input would be appreciated, Thanks