Six hundred. Seventy-four. Horsepower. At the wheels-all four of them. At a 5,500-foot elevation. Chew on that for a moment... spit out the gristle of correction factors, dyno type, yada yada yada, and digest five inline cylinders of 20-valve turbocharged goodness. And the aperitif of 599 lb-ft of torque-also at the wheels-is simply delicious. This is an absurd portion of power, however you opt to cut it.

Purchased new in 1993, Hap Maguire's been playing with his Ur-S4 for nearly two decades and has spent thousands of dollars in trial and error. His latest lunacy has manifested itself in a 2.5-liter stroker whose output summarily eclipses that of even the stalwart Sport Quattro S1's mere 591 hp. Collaboratively masterminded by the apparently deviant and diabolical minds of Dave Jones of S-Line Motorsport in Denver, Colo., Brendan Rudak of Apikol in Boulder, and Javad Shadzi of 034 Motorsport of Freemont, Calif., Hap's build paddles its own canoe with Paul Bunyan's hands.

The build stats are not for the squeamish: an E85-fed, titanium valve, ported, polished, and Swain-coated and flowed head with solid lifters, HD springs, and titanium retainers is supplied with a biiiiig SX Performance 18203 external fuel pump and before/after Fuelab inline filters. Injector Dynamics 2,000cc injectors accompany a polished Wagner port-matched intake manifold and an 034 Motorsports fuel rail and 70mm throttle body to ensure enough mojo is sent to Wiseco 83mm pistons atop titanium Carrillo rods with ARP bolts.

A practically erotic S-Line Motorsport equal-length and firing-order-sequenced stainless exhaust manifold powers an Innovative Turbo Systems F272 triple-ceramic ball-bearing turbo and Tial Sport V44 wastegate that's good for 825 hp. It's also about the size of my feeble cranium. The 105mm turbo intake with AEM air filter blows through a 24x10.5x4-inch front-mount Garrett intercooler with Apikol polished end tanks and 3-inch polished aluminum plumbing from turbo to throttle body, with a hard mounted Tial blow-off valve. A NOS spray-bar activated at WOT and/or on-demand is wound across the FMIC's face. The custom 3.5-inch downpipe breathes out a Magnaflow exhaust that splits into twin 3-inch (in) Magnaflow boxes with dual 2.5-inch (out) tips whose install required "maneuvering" the spare tire well. Synthesizing the synapses is 034 Motorsport stand-alone software, capping the fun at 33 psi with gear-dependent mapping.

Suffering stat overload, it's time to WOT this mofo.

Firing up such a complex creation is surprisingly simple-a brief kick of the starter summons the iconic five-cyl to a cam-tastic high idle of 1250 rpm. E85 wafts across your nostrils with a near exotic and addictive allure. The bespoke Southbend race/street clutch and lighter (by 17 pounds) 034 flywheel don't have my left calf palpitating nearly to the degree I expect to cope with this level of power, and uptake comes with deft ease and a satisfying, subtle grab. Testament to Audi is the Kluge-rebuilt OEM six-speed ready to repeatedly withstand in earnest what I'm about to dole out, while the Stasis-tweaked center Torsen differential ensures optimal torque split.

Petering about town, it's much like my old S6 or one of the dozens of other modded Ur-Ss I've piloted-tame, tractable, docile even. Folks often deride and chortle in turbo-lag mockery when peak horses and turbo sizes of this magnitude are uttered. A quick perusal of the dyno plot reveals an entirely vast expanse of area "under the curve." Maguire is putting down more power at 4000 than most chipped Ur-Ss are making at peak. Then consider that area under the curve is exploited by a 6-gang 'box coupled with an 8000-rpm redline, and pundits are enlightened. Precision shifts are delivered through the Apikol short-shifter combined with a lead-filled shaft and shortened lever, as operating temps are monitored through myriad mission control gauges: boost, EGT, AFR, oil pressure and temp, coolant temp, voltage, fuel.

By Paul Krasusky
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