Project Audi S4 - Part 3

To see if it was indeed a fuel problem, I mixed in several gallons of 100-octane race gas, and the hesitations stopped. You've got to love California's unleaded 91 octane-now we're forced to add a few gallons of expensive race gas to avoid blowing up our high-performance motors-how convenient. With 93 or higher octane, one should be able to run Level 2 straight and enjoy the additional performance of 14.5 psi with no problems.

I saved the best for last-Level 3's race gas setting. I contacted Down's Oil Company, a large distributor for Sunoco Race Fuels in Corona, Calif., and acquired some of its GT 100 Unleaded gas. The Antiknock Index (R+M/2) of this fuel is 100, with Research and Motor Octane ratings at 105 and 95, respectively. The fuel is street legal, designed for high-performance street cars, motorcycles and karts, and contains no metallic compounds to harm catalytic converters and oxygen sensors.

I ran Project S4 dry of the pedestrian owl piss it was using and filled it with straight 100 octane. Eagerly, I jumped in and started it up. I set the cruise-control switch to the race gas setting and drove around for a minute, giving the car a period to adapt and to make sure the 91-octane fuel was purged from the fuel line.

I shoved the accelerator to the carpet for the first time and couldn't believe my eyes. Everything was moving so fast! The tachometer zipped to redline in first gear before I could respond. As I climbed through the gears, within seconds the speedometer had me wondering whether I was going to make it to my dinner date with my fianc that night-not because the car wouldn't make it, but because I might have only one phone call to tell her I'd be late-very late! With the race gas setup, the car felt like it could take on the world.

It was then that I began to believe APR's claim of a 12.9-sec. quarter-mile run at 108 mph with this exact setup (visit APR's website and download the video). APR's Stage 2-plus kit for the Audi S4 is no joke. With the 1.0 bar setting on pump gas, an APR-tuned S4 will most likely pull on many of the high-performance European cars out there today, including the E36 BMW M3 and the Porsche Boxster S. On the 100-octane setting, you'll have Porsche 3.6 Carrera and BMW M5 owners asking what you've got under the hood.

Next time we'll strap Project S4 to an four-wheel dyno-I'm hoping we'll see 300 hp at the ground.