yea i noticed a difference in how fast rev's go up and down. it seems to pull harder up top, although when i first got it in i wanted to see how 1st gear pull was and spun the tires all the way through the gear. which it never did with the 38lb one. but it feels pretty normal though, i would really like to have a lighter one. (10lb) it made a difference but not a huge gigantic improvement.