I can't stand the look of USDM bumpers with the slats cut out. Only one I've seen that I can actually consider decent is Mark's from AMS. IMO, it just doesn't look right because the intercooler has to sit so far back to clear the bottom part of the bumper, which makes the upper part look like it's sticking out even farther than it actually is...that and you can see too much gap between the sides of the intercooler and the inner part of the bumper.
I even wish I'd not cut out my JDM bumper, but I don't think it looks as bad as cutting out a USDM one, so I just live with it.
Here is what I did with mine back in the day:
I just cut out the big middle piece. Whatever you do you'll need to touch up wherever you cut with paint to hide the black urethane.