Real world dyno testing is what Dyno Cell is all about. We constantly hear stories about a product making "X" amount of horsepower but when tested the power produced is most times much lower than stated. Dyno Cell is way to keep manufacturers in check and keep them from posting absurd horsepower increases from their products. When we heard that Stillen was claiming 16 horsepower at the flywheel from their 350Z exhaust system we had to find out for ourselves. We have performed several exhaust tests on the 350Z in the past and the biggest gain we have seen was about seven to eight horsepower. Claiming 16 horsepower would double what we have witnessed. So we found a bone stock 350Z with 20,000 miles on the odometer and took it over to Stillen.
Upon inspection, the Stillen exhaust system is considerably different from those we have tested previously. First off, the Stillen exhaust is a true dual exhaust system with two mufflers and a cross pipe. A previous system we tested utilized the factory "Y" pipe but the Stillen unit replaces the stock piece. The Stillen unit connects directly to the factory catalytic converters and then merges into an "X" cross pipe. From the cross pipe, the system splits into two individual exhaust systems, each section with it's own muffler. Constructed from polished stainless-steel the Stillen unit is mandrel-bent for uninterrupted exhaust flow.
On the Dynojet dyno the untouched 350Z generated 244.2 horsepower and 236.7 lb-ft of torque to the rear wheels in with the stock exhaust. From our testing this was the highest output we have ever seen on a stock 350Z. Best yet, the horsepower number was produced on aftermarket 19-inch ADR wheels with extra meaty Toyo Proxes TS-1 rubber. We thought for sure Stillen was going to have their work cut out for them.
Once the engine cooled off the Stillen exhaust was installed. We were pleasantly surprised to hear how quiet the system was. It was barely louder than the stock system. Once installed, the 350Z was back to the dyno.
Our very first pull registered 255.6 horsepower, 11.4 horsepower more than stock. By monitoring the coolant temp and air temp we were able to perform accurate "A" and "B" testing. By the time the factory ECU fine-tuned the program for the increased exhaust flow we were left with 258.0 horsepower and 245.4 lb-ft of torque. We witnessed an increase as high as 14.0 horsepower at the rear wheels.
Stillen claimed 16 horsepower at the flywheel so 14.0 horsepower to the ground isright in line with their claim. We will be the first to admit we didn't expect the Stillen system to make the advertised claim especially with a 350Z rated as high as the one we tested. That's impressive!
The Stillen system does carry a hefty price tag of $1150, but then again it did make twice as much power as any other 350Z system we have ever tested so you make the decision. It's time for us to burn some rubber under the guise of testing...there is life outside the dyno cell ya know.