I need help deciding which way to go. My main concern is having to tune on the rex to much. I know the Standard Bore 750 Kit is 11.5 to 1. What compression is the 840 Big Bore? What compression is the stock teryx? If the Big Bore is closer to stock compression it should be easier to dial-in and walk away. Assuming the high compression 750 is anything like a SB Chevy temperature changes affect how lean/rich you need to be. I live in Iowa so it could 100 f. and high humidity and 3 to 4 months later 20 f. I'd really like to go with the standard bore but if the 840 would be easier to tune and start I might go that route. I guess if the 840 is hi-comp as well I just wasted everyones time but the way the piston looks it must be lower. Thanks in advance for any help.