Its a big cost but... a DETROIT TRUETRAC is amazing in how well they work. I've put them in three different cars and love them. (got one in my 89GT)
Its like the thing is just smart. Instead of kicking the rear end out with a stab of the throttle (especially in the wet) it just goes. No matter how steep your turning. It takes much heavier throttle to get the rear end loose or squeal the tires. My 60fts are generally 0.15-0.2 better too
Its not a cheap unit.. but IMO its worth every penny.