300 hp = new cams (not gonna happen) and lower compression pistons. No other way I can see it. The celica gts world has been waiting for how many years for this kind of setup?
Don't get me wrong, technically it is possible to make some new cams and pistons. Unfortunately if it isnt an official lotus production, I seriously doubt we will see tuners step up to bat if they haven't already. The cams are going to require special machinery/processes to manufacture which only toyota/yamaha possess right now. Lotus could convince toyota to make a limited run of a specialized cam, but noone else out there could.