Project Viper GTS: Part 6 – Corsa Exhaust and Kooks Green Cats

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From any angle the exhaust looks great, especially the pronounced 4” chrome, double walled exhaust tips that really give the rear of the car a great look.

Now that everything is installed, we had to put it to the test.  We were ready to go back to our friends at Power By the Hour in Boynton Beach, FL but unfortunately the weather in Florida was a good 15-20* hotter than the baseline numbers.

After waiting for months for the weather to cool back down, we had to settle on a 95*F day.  We turned the rollers on a good 10*F hotter day and wasn’t sure what our new Corsa Exhaust and high-flow Kooks “Green Cats” would make.

We were ecstatic with the result.  475.38 hp and 506.96 lb-ft of torque is an impressive 23.55hp and 13.79 lb-ft peak to peak increase with gains across the board from as low as 2,600rpm.  The combination of the 3” Corsa Performance exhaust and Kooks “Green Cats” really improved the engine’s breathing in the top end with a 20hp+ increase from 4,700rpm all the way to the 6,000rpm redline.  The result is line with cat deletes and aftermarket cat-back exhausts which supports Kook’s claims that their Green Cats    “Only loses 1-2 HP going from off-road to catted.” 

Next up was to upload a tune from Roe Racing designed specifically for our K&N Filters, smooth tubes, high-flow cats, and 93 octane.  The procedure is quick and easy with the SCT scanner.

With the day still scorching on, we took the car to redline to see what the new tune would make.

At first glance we were a bit disappointed with no peak gains and actually a loss of less than 1hp, but that does not tell the whole story.  There were significant gains in the low end with a maximum 36.63 lb-ft of torque and 16.23 hp at 2,326rpm and 20.78 lb-ft of torque and 17.07 hp at 4,306rpm giving the car a peak torque of a massive 527.62 lb-ft.  On the street, this off-idle and low rpm increase is night and day, while the torque hump at 4,300rpm and the massive 20 lb-ft of torque increase at 4,300rpm makes for a noticeable increase in the seat of the pants feel of the car.  We did not get AFRs and will be making the provisions for that and will revisit the tuning in a future article.