The magnet does not provide direct lift to the top of the rocket. It merely transfers the thrust from the engine which is still at the bottom. But then a rigid steel beam does that as well. So nothing new, You'd probably find 100 miles at 100mph is far more efficient: higher gear etc. But that aside, you still haven't explained where you think the additional thrust comes from, rather than it just being a transfer through the magnets. Hint: there is no spoon.