There is a guy on KA-T.org who has the same turbo (
http://www.ka-t.org/forums/viewtopic...&highlight=hks) and he is making the same power and no more. Your simply maxing out the turbo. For a ka 2.4L the gt30r is best suited for turbo applications. I would assume since you have 2.35L the 30r would be best upgrade with almost identical lag, but I personally would put on at least a 32r as you can always turn down the boost if you dont want the power now... always leave room for latter.