Actually I did very few mods to my FRC, the biggest being adding an external oil cooler. Dropped my oil temps by 30 degrees or more.

C5Z obviously has more performance than the FRC, but is more expensive (duh!). The main differences between the two cars is the LS6 and the MN12 transmission, which has lower gear ratios. C5Z is a bit lighter, but not enough to make any real difference.

So, I'd look for a FRC/C5Z or C6 coupe. IMO C6Z is an awesome machine, but costs are a LOT more, both in purchase price and consumables.

Have a good one,
Mike