I also just locked my front diff yesterday, and for me it drifts considerably better. It's a lot easier for me to hit long sweeps, but it's a bit harder to maintain traction when needed. (This is just on rough asphalt though, not like freshly paved or any good drift surface) As for performance upgrades, nothing really that'll make a noticeable difference, you can get the metal motor mount to help dissipate heat, the carbon fiber upper body, stabalizers, but I'd go with a new body first if that's what you need.