Help Olympiad +6 Stuff

So a friend of mine is starting a new pvp server and i told him that the olympiad will be more balanced if itens is +6 stats/hp bonus

exemple :

i can go olym with itens +30 , but inside olympiad arena the status/hpbonus is like +6

i have tested to put enchant limite on configs like +6 or -6 or another number but didnt work

there is a mod or anything else to change that ?