I dont have exact numbers to what they would add to a perfectly working motor, my old piston rings were not in the best shape, the #3 cyl was about 40 off of the rest of them. So i can feel a big difference, at least down low. I paid 373 for the pistons from inlinefour.com and 40 to have them pressed on the gsr rods, i did the rest, i just had to buy oil, i had assembly lube and thats it!