Brake upgrade 150GY dual sport

Anyone know if there's any upgrade? Bigger disc or 4 pot caliper?
Front brakes below par even with new master cylinder caliper and Ferodo brake pads
Chinese caliper not good and I also suspect it's not square either in the bracket or fork, nothing to really check it with
Basically I bought new set up but still not happy with it, mind you the stupid mechanic that put oil on them aaaaaarg I did clean it off fit cheap pads and after a lot of riding cannot see evidence of oil coming from disc or on old pads ( cleaned oil off just after he did it)