Does anyone know the spring rates between the 4-door, 5-door, and Speed? I thought I saw somewhere that the fronts where the same for the 4-door and 5-door but, the rear 5-door springs would sit slightly higher when installed in a 4-door.

The reason I ask, I wonder if I could find some Speed3 springs cheap from someone that went with aftermarket springs. Just not sure if they'd make it sit @$$-high.

 

If they are the same physical size they shouldn't sit noticably different. I'd be concerned that they are a different rate, and different length - since different struts are used there could be some big differences between the normal and speed models.
There's also less than 50# difference between the 4 door and the 5 door, so the rears shouldn't make a difference in height either.

But looking at the mazda website, the 5 door is 3064# with the manual, 3124# for the auto, and the speed 3 is 3272#.
About 60/40 weight distribution, so 1900# on the front axle, 100# difference on 1900# isn't a whole lot - so it shouldn't sit noticably different than stock. Again, assuming the overall spring length isn't different as well.

 

Thanks.
I would change the struts and shocks as well. I was thinking that if I put the Speed springs under it that it would lower it a little and give it a sportier feel. If I could get them from someone that swapped theirs out then it would save from buying brand new lowering springs.