notchy shifter for b3000

looking for some advice, have a 2001 b3000 with 5spd and 9,000 miles and have always had notchy shifting problems since new. mazda installed new trans with no change, once it went out of warranty i installed new slave & master cylinders & bled, also mobil 1 trans fluid used. big improvement overall but i can't get rid of notchiness, between 1st & 2nd the most often, am not speed shifting, helps if i shift early but still feels like getting hit in the hand with a ball peen at times. heard something about using additive to INCREASE friction for synchronizers. any help would be appreciated.