I'd say don't do the 555R's. They are a pretty hard compound and I ran them on my Cobalt and they wheel hopped and wouldn't hook much better than my normal 555's I run all day long.
The normal Nitto 555 is an amazing tire though for Daily Driving and weekend "joy rides". It lasts a really long time for such a tire (over 40k and still tons of tread! like 40% still left!) And they grip nice as long as it's not to cold out. I have had success with the normal 555 and have purchased a second set (18 inch) for my Cobalt.
The 555r on the other hand was pretty much a slightly better drag version of the 555 and didn't last long nor did it help really at the track.
I'd try to find a cheap set of 18 inch wheels that will fit on the brembos and run a real cheater slick or true slick with a lot more side wall. You will like it more in the long run and the effect on your times will be impressive! plus they will last seasons and seasons while the 555r won't last very long! Good luck!