The theoritical equation works out to about 178-180
However, to properly align expectations the car will never see that speed because of tire friction, wind drag, etc....top speed will be sub 140 IMO. Another thing to remember is the OD gear in trannys are rarely (if ever) designed to allow the car to acheive 5500 RPM while in them. The car's top theoricial speed is best calculated using the 1:1 tranny ratio since in a race you would not be using OD.
Here is a theoretical speed graph I made for my car so I could have an idea of speed based on RPM since the speedo hasn't been hooked up. If I stepped up to a 28 inch tire from a 25.5 I would have very similar numbers to yours. While no one has yet to pass the car 5000 in OD feels extremely unsafe because of lift and I know I am not going anywhere close to what the theory says I should be (I would guess sub 110). So to answer the core question at higher speeds and air damn/spoiler on the front will help you prevent lift (until a point) I see little benefits in side skirts.