You got a thumbs up from me. You can see the improvement so just keep going doing what you're doing.
Boosts.... sigh. Just stop using them completely, as you clearly don't need them. They immediately make a stunt look basic and cheap and the ones you did without (which was most, in fairness) were much better. Literally, just don't even put them in your races any more.
But yeah, end on a positive note - definite improvement so do more