220 is probably a little bit aggressive imo I would have done 320 or 400 wet sanded if not scotchbrighted. I have to recommend you clear them or the nightshade shtuff starts to turn a bad satin finish pretty quickly.
What he said^
Around where I live, it seems like everyone discovered nite shades all at the same time. Everyone just went home and sprayed their lights...'got tinted lights now dawg.' My buddy who runs a bodyshop made a killing tinting lights the professional way and using good clear.
My buddies old R/T Dakota. Professionally tinted and still so dark that HID's didn't help much. It's just a give and take when you tint headlights. They do look good though usually. When are you putting your cobra bumper on?