The Curb weight includes oil, coolant, etc.
Just add the driver's wait and you will be fine. I could never get my GTEC's Dyno to work right. I had 314rwhp and all the GTEC showed was 265rwhp.
Maybe you will have better luck.
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'94 Cobra
308ci, ported GT-40 heads, Crane 2031 cam .513"/.529" lift 276°/282° duration, 70mm TB, Custom 80mm MAF, JMS chip, Vortech S-trim 8#, MSD, TREX fuel pump, Accel coil, 3.55's, FMS 1 5/8 headers, BBK Offroad H-pipe, and 2-chamber flows.
1994 Mustang Cobra
Check out the pics of my Motor Buildup!