Yeah, lower it. You have almost no wheel gap as it is, but I think it would look great if the wheels were tucked a little bit. Seems you need to get 1 inch larger wheels so they tuck, if you lower the car with the stock wheels, it just seems to give it the same wheel gap you already have now.

Also if the front wheel tucks, you may not be able to put in the spacer, because that would push the wheel out and it may hit the fender. Even if it doesn't touch at rest, it could cause it to hit the fender at full lock or over bumps. That's something to be concerned about, with or without the spacer, since you actually have virtually no wheel gap as it is.

If you don't lower it, definitely put in the spacers.

Although my xfire isn't lowered, I've done plenty of lowering work on my old car (green eclipse gst in pic) as well as buddies of mine cars. We had my one friends '97 M3 BMW absolutely slammed to the ground, wheels tucked deep as heck, only he couldn't go full lock or drive with passengers in the back seat. It looked great but I imagine those were some major inconveniences when driving it all the time! Anyway that was his decision to drive a car like that, just be aware of what your possibly getting into.