I was originally running 550 front and 250 rear springs on Dust Off with my DSE sub and G-Link 4 link rear with AFCO double adjustable shocks all around. I had a problem with the car porpoising at speeds above 110 which the shocks could not control even with maxed out rebound settings. I thought the shocks were the problem but before I did anything I contacted Rod Prouty and after discussing the situation he recommended upping the spring rate to 800 front 300 rear. After installing the new springs I was able to tune out the porpoising without having to max out the current shock settings. I was concerned that street ride quality would suffer but I was pleasantly surprised to find that by using a softer shock setting on the street the ride was surprisingly smooth. Based on my experience I would not hesitate recommending higher rate springs with double adjustable shocks so you can tune for both street and high speed track.