Yes it is common to find the Sport Brakes (340mm) on THP200's and HDi's, but not always. You can upgrade the brakes on the THP156 to Sport as well, if not they came with Standard Brakes.
Don't think that because you have 19" wheels means you have the Sport Brakes either, as 19" wheels are an option in some cases.
Having a GT or Sport model again may not necessarily mean you have certain brakes because Peugeot has changed things over the years.
I have done a lot of research on the brakes for the RCZ and as Abzynthe stated, the easiest way to tell what brakes you have on the front is by looking for the backing plate (aka dust shield). If it has one then you have the Sport Brakes (340mm), if not then you have the Standard Brakes (302mm). The rear brakes on all RCZ's are the same no matter what model etc. you have (excluding the 'R').
If you ever doubt what brakes you have, contact me and I will assist you.
If you are looking at brake upgrades it is paramount that you know what brakes you have currently because the kit you buy must fit the current caliper mounting setup and they are different between the Standard and Sport brake systems.
We offer Brembo currently but for Sport brake systems. We will soon carry Tarox for both Standard and Sport. We also carry Black Diamond upgrade discs for direct replacement for those of you wanting drilled, slotted etc. style discs.