There are both pros and cons to changing out the carbs. First of all, let me say that there really is not a huge gain in power, just performance. That means it runs better, starts better and has faster response. But on a dyno there are small increases.
Frank has the Mikuni 42mm flatslides (with accelerator pumps, that need to be disabled) from Bonneville Performance (about $1200+ but also includes airbox eliminator assembly, cables and controls), I made my own set of Mikuni 36mm flatslides (no accelerator pumps) from a pair of carbs I bought from Pro-Flo for about $300. A new throttle cable, a 6" piece of aluminum channel for a brace and new air filters since the stock/freak K&Ns ones no longer fit. So I got about $400 into mine. Plus many hours of dicking around making the cable and drinking. Member biker (Ed) has the same carb setup as mine and I basically copied his. Neither of us has had any problems whatsoever in over two years of running them. And parts are a dime a dozen at pretty much any mc shop in the world. They are nothing fancy and I do have to use two chokes to start it, but only when when ice cold, but no biggie to me. I do still need to do some more jetting work but it's snowing and the snowmobile is taking priority now.
