safe boost

Hello everyone! Im new to this forum and not a social media person at all.. anyway besides the point, ive had my HDJ80 for almost 6 years now and slowly chipped away doing upgrades/mods on my budget and recent put on a hi flow ct26 from cct turbo. The cars just clicked over 600xxxkms i replaced...

Howdy! Just a quick little one guys. Ive got a 120 TD with a 3"exhaust(1Kz-te). Wondering how high i can safely turn the boost up? Standard is 10p. Also wondering if im going to start playing around with boost control if i should get a better air filter or not worry too much? Cheers. Jesse