Hi, I have 2 Rossi .40 engines, both without carbs. I am considering purchasing 2 perry carbs for these engines. the Original Throat diameter of the rossi carbs is .270 in which is about 6.8mm. the newer rossi engines state that the have "10mm carbs for power, as opposed to the 8mm carbs for fuel economy" does this mean that I could actually get a larger bore size such as the .315 in (8mm) dia. throat carb, and get more power ( or even the .340 (8.63mm) or .375 (9.53mm) dia throat)? has anyone used a larger carb on these rossi .40 engines, and what kind of success have you had with them? Or should I stick with the stock size?? any input would be appreciated!! I have asked the Rossi importer, Rossienginesusa and thier response was less than helpful , it seemed that they weren't sure, so they suggested that I stay with the stock size? any ideas/suggestions?? Thanks, Craig.