Aluminum Radiator
 

is an aluminum radiator for an 04 mazda rx8 better then the stock original thats already on?

what would be the difference?

it says it'll keep my engine way cooler then the stock but i wanna make sure it does before i buy or if i buy

Your question is too vague. Give more detail.
Also, have you searched the forum for a possible answer? This has been discussed a few times already...

The stock radiator (or OEM replacement plastic tank from Koyo/Calsonic) is very good. There is little to be gained from buying a larger dual core aluminum one.

Now stop starting new threads and search.

You can get a thicker core, I have plans for one someday. The thickest radiator I found was a 1.57 by both Mishimoto, and Mizu, I don't know which is better, but a thicker core usually cools better.

if you can flow air through it.
it is actually better to have a thin core and additional face front size--but due to space limitations--thicker cores where developed.
If you go to a thicker core than oem you really need to upgrade the fans and their controller too.