He passed me so I was like wtf aint having this so next red light he revved at me and then I powerbraked it and stomped him.
Then there are several possibilities.
1: He didn't know you were racing him.
2: It's broke and or worn out.
3: It was a 4 or 6 cylinder.
4: Manual transmission and he can't drive.
5: Automatic and it's slipping.
A mid to late 80s Mustang GT runs low 14's in the 1/4 mile stock and around 6 seconds 0-60. Even a highly modified Sonic can barely keep up, forget about stomping one.
Just so we're clear, I don't like Mustangs but I do know what's realistic.