Who makes the best bushing kit?

 

There is no best. Your choice should reflect your intended use (or desire). I personally just started updating the bushings on my daily using "hard race" bushings.

 

I'm looking for good durable parts aimed at autocross

 

Bushings will help with either assuming yours are original and worn out or ripped. On one car I have some energy suspension polyurethane bushings and they are nice. On a different car I have been going with some Hardrace products.

If you are making a dedicated track car why not go with spherical bearings?

 

Make the switch to energy suspension bushings. Expect to change them every 1-2yrs especially if you daily drive the car. Yes they do wear out that quick, but they are easy to change once you've switched from stock.