Back in 1999 was the last time I had my 93 on a dyno. It put out 404 hp and 471 lbft of torque with SVS headers and Borla XR1 mufflers on a chassis dyno. The prior exhaust was the two-piece stock manifolds and no cats, with 3" Borla XR1 mufflers.
While the overall power output numbers were similar, there were improvements in the lower range with the headers. Compare the red line (with headers) to the blue line (with factory manifolds). I guess it shows how well the factory two-piece manifolds flowed: overall they were only 2 horsepower and 11 pounds of torque, less than the headers!!!
I attached the original dyno sheet (ignore the green line and the "new computer" comment: that related to the dyno shop's laptop computer which crashed and altered the existing data files and correction factor)
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