Are there any aftermarket components that will be an upgrade for the cooling system in these cars?

Depends on your intended use.

The best way to cool the engine is to install an after market radiator and a SEPARATE oil cooler. Then use water wetter in your coolant.

I'm the weekend driver, nothing serious. I just did a search for radiators and came up with Dewitts? How is that one? And where would i mount the oil cooler?

I'm the weekend driver, nothing serious. I just did a search for radiators and came up with Dewitts? How is that one? And where would i mount the oil cooler?

Dewitts and Ron Davis are both great. As I said, make sure you DON'T buy their model with the oil cooler and radiator built together. I've owned that and isn't not nearly as effective as a separate oil cooler.

Here's one way to install (ergo mine)

It's located just inside my intercooler for the SC.
http://farm2.static.flickr.com/1289/1360279416_e4c2748f8b_o.jpg

Thanks for the photo, though a C5 it does give me an idea. :cheers: