I weighed the slotted ones and it was about 30lbs savings. And the car felt better in the turns up in the hills and accelerating. They are awesome rotors and well worth the money. Theres a reason they use the Stoptechs on the new ACR.
And as far as question about power. I dont know how rotational mass translates into hp, but I know it makes a huge difference. I had posted a video. ILLSMOQ and I ran against eachother from a 3rd gear roll a week before and I got maybe a 1/2 -1 car on him. Then only change was my Stoptech rotors and we raced again. I put like 3-4 cars on him just from 3-4th gear. I had heard every 10lbs of unsprung weight is like a tenth in the quarter mile. It definatley makes a difference.
I've been trying to figure out an exact formula too...but it's actually a bit more complicated than I thought.
Not only does the weight have an effect on the performance gain, but the distribution of the weight has something to do with it as well. example: A 40 pound wheel with a diameter of 28" is going to have more rotating mass than a 40 pound wheel that is only 26" in diameter. 20" wheels with 335/30/20 are 28 inches and 18" SSR's with 335/30/18 are 26 inches (and very light)
Also the speed the item is rotating is significant too. example: loosing 10 pounds from a part that rotates at engine speed will provide more of a gain than loosing 10 pounds from a part rotating at wheel speed.
At some point in my quest of understanding rotating mass and the performance gains of going lighter, I ended up
HERE .....I spent a few minutes looking at the page, then shrugged my shoulders
and turned on the X-BOX
as for MikeR
there....yeah it was crazy, I couldn't believe he went form pulling ahead by a little bit to walking away from me pretty hard....made a believer out of me so I picked up a set of drilled stop techs and a few other parts too. With the rotors, 3.55's and a few more ponies, 3rd gear rolls I walk Mike pretty good