Not to split hairs but based on another thread on here the springs are also different.
Following recent discussions about which springs are on which of the current 500 range i have updated my parts list.
there are 3 different rear springs in use,
Standard 135 hp 51805424
500C 51859960
Comp, Turismo,Maserati 51939102
this reads slightly differently to the previous version which suggested turismo/comp were both different depending on whether they were convertible or tin top.
.
the mods were made to the suspension spec from october 2012 so the situation should have settled down on new cars coming through now 
How long were you researching that

Still most people who have driven a 500 on 16s and 17's will tell you the ride is better on 16's despite it being a
500c (on a slightly different suspension setup) or a 500.
Have you driven on 16's and 17's by the way, what is your view.