I ran a 10.84 with a Comp 529/543 250/256 108 lsa, with the exact same set-up I ran the 10.75 with the 590. So to Bob's point, it will run quicker & faster but you will have to spin it to do it. I could run 10.80's shifting at 5800 with the old cam, but I had to spin 6600 to get the 10.75. So if you decide to go the 590 route be sure to check your spring pressures, retainers and locks, things like to move around at the higher rpms - dropped valves have a fun rating of -8. BTW I have my old cam for sale if you are interested.