It's hard to say if you would have problems if you didn't install the axle back with all of them. If it were me, I would just have the dealer use all of them. You paid for them, might as well put them to good use. Besides, what are you going to do with the extra ones if you didn't use them all? They aren't good for much else...now a mazda dealer is doing hte install for me. if i understand correctly there are five in the box. now im just buying the tanabe axleback concept g mufflers. do i need to have all five installed or just the ones for hte muffler. andwould it not work if i just had the delaer install the muffler ones.