Yep, rule is 3% HP loss for every 1,000 ft elevation gain, so I'm down almost 200HP. Come spring I'll rejet the carbs and likely go down to 15" labbed props.

Rejetting or FI doesn't get the HP back, it just compensates better for A/F ratio, most guys here are running Superchargers to compensate for the lack of oxygen.

Rev limiter chips are 6000 rpm, remember the Great Lakes are above sea level too ~600ft so there's likely at least 1" prop decrease there from sea level already.