A Mustang dyno typically dynos about 8% less than a Dynojet. I'd venture to say ~205whp/260wtq on the Dynojet. The Trans Am of that vintage weighs ~3300lbs giving it a wheel power to weight of 16:1 or roughly that of a many mid 14-second cars (Honda Accord 6 speed, 2002+ Maxima/Altima, GTP). The problem though resides in the nature of the TPI motors. They build a ton of power low and then puke and die up top. As you can see in the dyno, peak power is achieved just below 5000rpms and after that it falls off to ~170whp by 5400rpms. Needless to say, these motors have very short powerbands which isn't terribly ideal hense the reason why you rarely see the TPIs tearing it up at the track nor do you see them running the same kind of ET/MPH as a different car with the same power to weight ratio. Long linear sustained powerbands (power under the curve) are what makes a car fast.
I'd guess this 305 TPI would be good for mid to low 15s at the high 80s. The 2.77 gear really isn't hurting it much and a 3.45 will probably overgear it because of the short powerband. I'd say no higher than a 3.23 series unless tall slicks are to be involved. The 2800rpm stall might help a little if slicks are going to be used, but the 2800rpm stall could overshoot some of the powerband.
When I had my 94 Z28 auto 2.73 gear with intake/exhaust/ecu, I hung out with three guys with L98s (350 TPI motor). When riding in these cars you'd swear they'd tear the LT1 a part. The power sensation was amazing, but that's because the torque curve hit hard and fast and then fell, hit the next gear and the torque hits hard again then falls. The LT1 just felt fast, but the L98s felt brutal. However on the track the truth was revealed. They got smoked by the LT1. I ran mid to high
13s@101mph and they were in the
14.5-14.6@95mph. Their 60' and 1/8 miles were slightly better, but I crushed them in the last 1/8. They could only gain ~16mph in the last 1/8 where as I did ~20mph. From the rear view mirror it was a steady and hard walk on the L98. When the LS1 was unleashed, I swore that thing felt like a dog compared to my LT1, but the truth was revealed to me at the track. They were significantly quicker and had VERY linear and long powerbands.
