Why is my car so slow?

[da89cup]

I'm running a 351W with a 9" K&N cone, 80mm MAF, 70mm tb, GT40 lower, Cobra upper, stock 5.0 heads, long tube Hedmans (1-5/8), no cats, 2.5" H-pipe, Dynomax race bullets, & 4" tips, 2.73s, 190lph pump, 30lb injectors, I bought the car with most of this stuff done to it allready, it has some kind of cam but I don't know what it is, my car idles @ 1000rpm, & I don't see a chip plugged into the computer so I'm still running the stock computer with the 5.8L. My best run was 14.665 @ 95.9 mph, my reaction time was .523. I hear of all these guys running almost stock Mustangs & they're getting low 14s. With all these mods, my car is damn slow. I know that if I get heads & gears, my car will just fly. I found a set of BBC heads bare for $1200 canadian. I'm not too familiar with BBC, can anyone give me some advice on these heads. If I get heads & 3.73s, what kind of numbers could I expect in the 1/4.

thanks