CBear916,
I think the Si coupe had 15 or so hp more than the EX coupe. There were other differences like rims, maybe thicker sway bars etc. Also, if I recall correctly, the Si had much taller gearing, so at highway speeds you were pulling something like 4k rpms. That's fine for getting off the line quickly...but there goes your gas mileage.
Anything can be made as fast as you want with a suitable application of money, time, spilled beer and skinned knuckes.
Bogatyr