I am just curious to know what the benefits and drawbacks are to the higher pressure radiator caps. I have a 21.3lb cap sitting here with nothing to do.

 

Higher pressure means a higher boiling point for your coolant. I believe it is 3 degrees for every pound, but I'm not positive on that.
The only draw back I could see from using a really high preessure cap would be putting excess pressure on some seals and hoses. But I doubt any cap you can buy at an auto store would be able to hurt anything. Just about any cap should be fine to use, I've even used duct tape before in a pinch. Although I hear the TRD ones give you a few hp.

 

only type R caps give horsepower... cmon, we all know this