What Happened!!!!

[COBRAon18s]

i dont know what happened but here is the story, i have a 1999 mustang cobra convertible with 18inch rims, an h-pipe, a rollbar, and a passenger. A single driver in a stock 2000 camaro z28 coupe pulls up at a red light. he said to punch it so i did. I know that i have ten more hp than he does, so i gladly took the race, we were neck and neck in first, but when we switched to second, he took off, won by about half a car, to my understanding, cobra's are supposed to be faster than shitty z28's, what happened, is the rims?? passenger?? or just a slow car????? here is a link if you wanna see my car, please give me your input. http://webpages.eng.wayne.edu/~aj3727/myride.html