Here is the scoop on the WYK33 for those of you who are interested. It flows identical to a WT257; that is 33 CFM at 28" of water and they both make the same power on the dyno. However, the WYK33 has a better metering circuit and transitions from idle to full throttle cleaner. That's why they seem to have better throttle response when they are set right. But the big gain comes when you modify the WYK33. Bore out the body of the carb and the barrel to .630. This bores the venturi right out of the barrel. This is the reason that you need to lower the pop off pressure after this modification, because the vacuum signal isn't strong enough anymore to pull the diaphram down against the stiffer stock spring pressure under the needle arm. Then you counterbore the front of the carb and JB weld a radius entry into it. Now the carburetor will flow 43-44 CFM at 28" of water. This is where we get the 1/2 hp gain. The reason we don't modify a WT257 is you can bore the venturi all day long as big as you want and it won't flow anymore than 33 CFM. You can even bore it so big that you hit the needle bore going down the side of it, it still won't flow anymore. This is because the restriction is at the butterfly and butterfly shaft. The best easy modification you can make to the 257 is to streamline the butterfly, screw, and shaft. If you take the butterfly out completely and plug up the shaft holes, it will flow 38 CFM. If you then start boring the venturi, you will start to see some gains. I have ran these carbs with no butterfly on the dyno and used the water brake to control the RPM and it does pick up power. Interesting though, you will notice that the standoff spray in front of your carburetor will increase with the butterfly missing. The trick is flow as much air as possible through as small of a hole as possible.