Think this intake swap will hurt performance?

Do you use a shift light? I would try lowering your shift points to slow the car down. You can add weight by running with the gas tank full or adding weight in a safe location.

You can hit a test and tune where you have an opportunity to get a few passes in. You need 2 baseline passes then try shifting 200 RPM sooner via the shift light for a pass. Next try shifting 400 RPM sooner.

You will also want to repeat the testing by adding know weight amounts to the car.

Between these two variables you should be able to adjust your ET to the index in varying weather.