performance upgrade time

its winter and time to think about next years outings in the elise. it is standard at the moment and the thought was to fit janspeed sport exhaust(oval as per exige) from PTP with cat bypass(after MOT), also ITG airbox kit, possibly have the chip retuned(motobuild have done this on a mates elise and it boosted the midrange.the goal - better sound, better performance(circa 135hpis ok??), but still usable and not costing the earth.any comments appreciated.