All walbro carbs are measured in 64ths of an inch - Meaning a 32 is a 1/2" carb. This is an easy way to tell how big they are when you're sifting through the second hand ones at your local repair shop....

By the information here, i don't think there will be much difference in performance but i run a 32 fine in my boat, i.e it won't hurt it.


Also, i have heard of some people removing some material from the butterfly around the idle jets on the bigger carbs. They make the crescent bigger (about 2mm deep). Apparently this greatly improves idle performance and it also means you can get better needle settings for a full rev range rather than tuning for idle.