Yea i used the HD bilsteins with rpm sport springs, and it's wihtout a doubt awesome. I use my ms6 as a dailydriver but i'm also pretty aggressive about my driving habits and my new setup suites me very well. I didn't need anything special for the front, but i don't know if the 03 mazda6 setup is the same as my ms6. Also the rear shocks were a pain in the a$$ to get to, there has to be some kind of special tool for that one.