Now that the Supersprint exhaust was installed, it was time to dyno again. When we first ran the car on the dyno, (pre-exhaust) I was nervous to say the least. My car already had the Dinan High Flow Cold Air Intake System and Dinan ECU upgrade (not really a "chip" anymore) and I had heard ad-nauseum about how the adaptive nature of the OBD II ECU software would show no power gains no matter what.

Running your car on a dyno is one of those surreal experiences you have to do once in your life. On a lift dyno, your car is roughly four feet in the air strapped to the lift, going 70+ mph The image of the car shooting off the lift keeps popping up in one's mind. Anyway, we do three baseline runs. They are all pretty consistent, with the best being 167.6 hp and 175.5 ft lbs of torque. Remember that this it rear-wheel horsepower and torque, not the crankshaft horsepower and torque as quoted by the factory.

After we installed the Supersprint we fired up the engine to warm it up, and it sounded fantastic, too. Stock, the car just didn't have a sporty-enough sound. With the addition of the Dinan Intake and ECU upgrade, it had a very feral howl, but only on wide-open throttle. The Supersprint exhaust added a "bass track" to the sound, sounding it out nicely. Now, full throttle applications combine the howl with a deep growl, making for a formidable sounding beast.

Below is an amusing animated picture Robert created from a couple still pictures his camcorder recorded. The first frame is from the "before" dyno test with the stock exhaust. The second frame is hours later from the "after" dyno test with the Supersprint exhaust (with turned up DTM style exhaust tips). I'm sure the angle of the exhaust tips had more to do with it than the amount of exhaust, but notice the Dynojet banner in the background. Now that's what I call a free flowing exhaust :)

Once we warmed up the car, it was time to dyno. The sound of the car running up to over 70 mph in what was essentially a one-car garage was a sound not easily forgotten. One alarming note, though, was the plumes of smoke emanating from the rear of the car. Turns out that it was the exhaust burning off coatings, grease, and other contaminants. It had a mighty stench as well, which I was told would linger for about 500 miles. I was glad I had a long roadtrip home.

Once again, we do three runs, and they are again very consistent. This time the best one is 171.7 hp and 181.1 ft lbs of torque. Click on the small portion of the graph to the right to see the full size before and after comparison of the torque curve. At the peak torque values, the Supersprint exhaust gained 5.6 ft/lbs of torque. Looking at the entire RPM torque curve and measuring the differences every 50 RPM the Supersprint exhaust averages a gain of 4.3 ft/lbs of torque between 2000 and 6200 RPM.

It would appear that this is an apples and oranges comparison, and it is somewhat. However, there are correction factors, and the one we'll use here has been ascribed to a well known Utah-based chip tuner, but I can't confirm that origin. This correction factor to convert rear wheel HP to crank HP is 1.21, or about a 17.2% loss. Given that, my numbers would work out as follows using the equation RW * CF = C, where RW is rear wheel HP or Torque, CF is the above correction factor, and C is the crank HP or Torque.

Stock 1997 2.8 - factory specs