I think the first mile split from the Garmin matched up pretty close to the first mile clock so it's probably pretty accurate.
After that the remaining GPS splits were really skewered (overall the Garmin had me running 5.52 miles -- not likely). What I do know from the official stats is that I ran the first 5k in 26:24 (8:30/mile) and my official finishing time above was an 8:31 pace. That means I ran miles 2 through 4.97 in the 8:25 to 8:30/mile range. Very consistent. Stats aside, this was easily the best race I've run. I found my pace very early in mile 1 & picked it up a little in mile 2 after I got out of the early congestion and hit State Street. From that point on, I had no problem maintaining that effort block after block. Going south on Franklin in mile 4, I ran into some pretty stiff headwinds, but just fought through them with the same solid effort til I turned east on Harrison. I continued to maintain the same solid, steady effort down Harrison until I passed State Street. At that point, there was probably 3/4s of a mile to go & I started picking out runners ahead of me and picked up my effort to try and reel them in. Maintained that increased effort to the top of the hill on Roosevelt & then picked the effort up another notch from there to the finish line. Felt very strong the entire distance & when I crossed the finish line felt like I could've run several more miles at the same effort & pace.