2003 Pontiac Grand Prix - Dyno Testing - Six Sense

We wanted Street Legal Performance and got it by installing the high-flow cat. A few weeks after the header/exhaust installation, we easily passed New Jersey's tough visual and dyno emissions test. Efficiency and performance can come together!

During dyno testing, we noticed a few degrees of timing being pulled out with the coolant temperature soaring over 200 degrees. We replaced the stock 195-degree thermostat with SLP's PN 100180 180-degree thermostat and installed the company's PN 63013 fan-control switch.

After draining the antifreeze and installing the thermostat, the radiator was filled with distilled water and Redline WaterWetter. The thermostat, fan switch, and coolant change kept the temperature well under 200 degrees (it averaged 185). This prevented the knock sensor from retarding the timing and netted us slightly more power to the tires.

Dyno Test Results - Notice the average torque gains and how much broader the power is under the curve as the original baseline and the Part II mods that encompass Part I mods, are compared. All dyno pulls were done on a SuperFlow chassis dyno with the GP in Third gear and the speed limiter disconnected.