I'm thinking of a mild carb upgrade to go along with my planned 3mm crank and port work. Noticed a few different carbs commonly available. What's the difference between a Keihin PJ carb and PWK? Price isn't terribly different. Is one better or easier to tune etc than the other? Is one more rebuildable or make better power? I'm only planning on a 28mm as I want to keep the best throttle response and a crisp low end/midrange.