Your stock 2.0 heads flow more air than your stock djet can use.
Bone stock 2.0 heads in the proper configuration of cam, springs, intake, compression ratio, bore, etc., etc.....
Can go past 140+ HP with no porting.
Jake Raby can get more than that out of 1.8 head with minimal cleanup.
If you want the fun of polishing the exhaust. Go for it. Pull the valves out first. I suggest you DO NOT polish the intake tract. Clean it up yes... Polish no. Better to have a slightly rough intake tract (like 160-180 grit) rather than a polished port and intake manifold.
Ifn ya wanna know why. PM me for a phone number. Too long to write it up.
By the way... if ya just happen to touch the valve seat surface while you are doing this. You are going to have to get another valve job. So duct tape is your friend if you use a small tool like a dremel.
If you use a die grinder like I do. It will chew through duct tape instantly.
Die GrinderBe careful. Look on the web for the DIY yourself port polishing web sites. And have some fun.
DO NOT PORT THESE HEADS unless you know a bunch more about head porting THESE SPECIFIC TYPE IV HEADS. These ain't chevy heads.
In truth. Polishing and/or porting. Based on your existing application.
Won't make any noticeable difference in your torque or HP on a djet engine.
That is my experience. Yours may be different.
Cheers and good luck.
Clayton