You can run any generic external transmission cooler, but I'd say it really isn't necessary, especially if you're not towing or putting it through severe service.
Lots of stop-and-go traffic in the summertime will heat up the fluid, but I think that's about it on a street car. Especially when the torque converter is engaged, the transmission fluid stays relatively cool and no harm is done.
I'd just use the OEM equipment. And personally, I wouldn't even fix what isn't broke (replacing the original radiator). If it's not overheating or giving you other symptoms, I'd leave it alone. But to answer your question, I don't think a "performance" radiator exists. Becool and other companies like that can make you a custom aluminum radiator, but then you're getting into some big bucks.