Piss off the EJ257 and buy a factory forged EJ207 - I understand are pretty cheap now days, strap a bigger turbo up boost and have fun. Won't be as responsive but will be a heck more reliable.
I've been through the same problem as you but... my 2.5l was running all the basic mods,
tbe, cai,
ecu etc etc. Yours however being completely stock... that really sucks... but hey thats the EJ257 for ya! sh1thouse