I'd say Lynx RS. Very good base car. Of course, modifying the Lynx isn't all about the oomph... There's an OEM kit good for another 30hp, used in USDM Mazdaspeed Protege. But if you want a much more powerful option, the Lancer GT (manual) might just be good too. Or how about converting a Mazda 3 2.0 to manual? Then slap some turbo! :D