That's crazy. Lowered 2" or more and they can impound it? Wow. We have cars here that can't even go over speed bumps their so low! Realistically you could argue 18" rims are fine as 17" rims are "Stock".
I've been contemplating going back to the sock ride height. I emailed Koni and they said the shocks work fine with the stock springs so I may throw them back in for a while.
The writeup looked good. I have a different engine so I don't think those would work with my car. Did you replace the spark plugs as well or just the wires?