I was one of the first ones to start the Q-52 carb trend going on the US 41. I had one of the older ones. I don't know what carb they are putting on those engines now. If I were you, I'd run yours and see what kind of rpms you get with an 18X10 Pro Zinger or an 18x8 regular Zinger. They should be above 7600 rpms. Also, get rid of the stock muffler. We run straight headers on ours and the open exhaust really makes this little engine come to life along with the right prop and carb. If you can get close to 7800 rpm with the carb it comes with by opening up the exhaust, then I wouldn't change the carb. If you are down in the high 6000 range to low 7000 range once you run the open exhaust, then you've got to change the carb.