The question should be approached a little differently than the previous 2 answers. You can not just toss out a generic one size fits all jetting answer. You have to figure in your altitude above sea level and average humidity as well as any exhaust or intake changes to get correct jetting. For instance where Ryk is his sizes may be correct but for where I live with pods and open exhaust my main is 155 and my pilot is 48 and that was tuned on a dyno with an exhaust sniffer. Reducing back pressure does not reduce torque unless you pass a certain threshhold. You want good flow with some back pressure. ( the actual best I have seen is with an adjustable baffle in a super trap with pod intake filters with the baffle adusted on a dyno) Depending how deep you want to get there are other changes you can make to the stock carbs to gain better performance like drilling the air bleed hole and changing slide springs and needles and needle position, etc....

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