After reading Bill's comments on pickup base plates, I looked for strat base plates and found a few companies that sell steel base plates (Callaham and Fralin for example) but I couldn't find any brass or aluminum plates.

The ads claim that steel base plates add more bass to the tone, I don't really want more bass, I just want more volume. I'd like to try different materials.

But for now I ordered an Callaham steel strat pickup base plate off ebay.