Pondering the total weight and weight distribution change vs a stock Miata… Depends on the car. V8R’s MSM was nearly a wash between the factory drivetrain and the full LFX swap from what I recall. I’m sure a stock naturally aspirated Miata would have it beat, but nobody is making 250+whp on a naturally aspirated car, so that’s apples to oranges. Compared to a turbo car, I expect this to have a better weight distribution – some of the rear components add weight over what is coming out (but are stronger), and in the front you’ve got a tubular subframe and all aluminum motor.
My weight distribution is worse than most would probably expect. That’s partly due to aero additions up front, and a lot of easy weight saving in the rear, but the turbo makes matters worse. For those who have seen my V-mount setup – that’s a big intercooler and other bits far ahead of the front axles, plus the turbo and cast iron manifold.
Currently I’m at 59% F / 41% R. I’ll double check that on the scales right before the tear-down begins and then scale it again with the new drivetrain, so we will have some solid answers by the end of things.