Noticed you were looking at different wheels threads. I think you should keep your wheels, lower it an inch and throw some 275/45 18 tires on there. They are only 0.9" shorter so your speedo won't be that much off. Only 1.8 mph faster at 60 mph.
Or go for broke, lower it 1.4" and throw some 285/40 18 tires on there. They would be 1.6" shorter, so your speedo would be 3.4 mph faster at 60 mph. Still not a big deal if you can't correct the computer. That's the direction I'm going with mine.