if u ask a builder ,u could get a wood/trail port done when they port for a 4 mill. call acouple of builders.. there is acouple of good one's on here. try F.A.S.T ,herrjugs,passion.
do it right, i had my stockers drag ported by a local guy and they ran great. but wanted to put a 4 mill in. i had no clue what my port timing was. alot of builders arent going to mess with someone elses port work. so do it right the first time.
tell them u want more low-mid range or whatever u are wanting,let them know what kind of riding your wanting to do.