The answer is simple. If you wanted maximun performance, you had to buy a Cobra, which was rated at 305hp. If i remember correctly, it was a faster car than all the LT1 Camaros and TA's.
the pre 99 gt's CAN go fast like every other car on the road. Just takes a little money..or in our case...a lot.
With pulleys, T/A, o/r X pipe, flows, CAI, 80mm MAF, and 4.10's with a set of drag radials, I ran a 13.89. with a 1.88 60' time. LCA's would have made it quicker.
Little tricks like pulling out the jack, putting a spare on each front tire, pulling out the back seat etc. can drop your et's also. Pulling the front wheels and putting on spares made a big difference by themselves.
Headswaps can be done these days for about $600~$800. Add on another $550 for cusom cams and another $1200 or so for port and polish work.
You're not gonna get better than high 13's without a power adder or new heads though.
only prob @ the track close to where I live is they will not let you run donuts on the front. no biggie though. I ran my time w/ 2 12's in a custom box & spare in the trunk w/ stock tires & 35 or so psi.