turbo is the only good option for the 5sfe(4cyl). there was a supercharger system for it but it wasnt very good, expensive and VERY rare. so if ya want high hp then a swap or a custom turbo will have to be done. If you swap however youll have to swap the engine AND tranny. many say it would be better to just find a V6 manual and sell what ya got...but to each their own.
as far as sites ya gotta be more specific. there are tons of sites that sell one or two items here or there(preformance, body, suspension). thats why i said ya gotta figure out what ya want, search that topic on the web and here in the forum and then if all that fails...ask.
ebay is a good place to search for goodies though