C/C plates would be a good idea just for the ease of setting your alignment so you don't wear tires or experience any drift/pull to one direction.
As far as a necessity, I ran the prokit on my car without c/c plates for 3 years with no problems.. Camber and Caster were both in spec,
so it didn't wear a tire, and didn't pull. That being said your luck may differ. Getting a quality c/c plate like Max Motorsports now, would benifit
you down the road, in case you decided to upgrade to coilovers etc...