I think the APC 6.5 x 5 was the best I tried with the little delta / CVA .15. The 7 x 5 sport prop is a good choice, but the 6.5 x 5 is worth trying if you get the chance. I've got the header cut pretty short and am using the standard MACs .15 pipe. The only other item is a C/L venturi...it's either home made or I took a OS venturi and hogged it out. I don't recall what difference it made VS the stock carb, but it's big enough to need either CC pressure or a combat bladder.