Italjet Formula125cc Restriction?????

Hi I have bought an Itlajet formula twin 125cc 2 stroke and want to tune it, while talking to a guy today with 3 of them!!! he!!...beleive it or not reckons there is a restrictor in the motor somewhere as he cannot get anymore power by installing endy pipes/twin flatslide 24mm carbs and a foam filter .....could it be the cdi that is limiting this sucker?????
Any1 have any suggestions ??
I was gonna do a single flatslide 24mm to both carbs plus numerous engine mods/endy pipes open filter bell etc.etc but if this the restricting factor will it be worth it /?????