Last year Volkswagen stirred things up at the 2005 SEMA Show in Las Vegas. Seems it wanted to show the world what classic Germanic tuning could do for its cars. VW's efforts yielded a trio of turbocharged vehicles that won't soon be forgotten. Hugely powerful, immensely quick and remarkably agile, they reminded us why we love VW cars. For 2006, the company wanted to see what the US tuning scene could do, so several American VW tuning specialists were approached to participate in a GTI Tuner Challenge. The idea was simple: while retaining consumer accessibility and building vehicles that an enthusiast could replicate, each tuner would create its own interpretation of the ultimate GTI. The winning entry would appear on the VW stand at the SEMA show in Las Vegas.
A tuner will normally develop a plan, then tear down the vehicle to its most basic components. Each part is analyzed and then re-engineered to reach the initial goal. There should be a balance between daily-driven practicality and something suitable for track use to exhibit racecar-like acceleration, handling and braking, while still maintaining street-going civility.
The criteria for the GTI Tuner Challenge was along those lines: good power delivery and smooth acceleration, a firm suspension with street manners, positive steering feel, positive clutch feel with precise shifting, clean and original exterior styling and paint quality, and a smart, comfortable, accessible and functional interior.
Performance testing was carried out on Dynajet dynamometer to determine exact power and torque numbers. And each entry made the trek to Willow Springs International Raceway in Rosamond, California, for acceleration and braking sessions, as well as hot laps on a pre-planned road course at the Streets of Willow circuit (adjacent to the full-length track). Results are listed in each car's individual spec box.
Driveability, Acceleration, Exhaust
Optimum acceleration is smooth and uninterrupted, with readily available torque. The car should have very little lag (preferably none), so there's no waiting until 5000 rpm for the power to come on. From standstill, the clutch should allow for easy take-off, with no chatter. The exhaust should emit a nice tone without any annoying drone-sometimes it's necessary to sacrifice a little power for sanity.
The ABD GTI's acceleration gives a bit of a fright, since power delivery is abrupt and creates torque steer. The clutch is a little touchy off the line, but once the car gets going this is no longer an issue. The dual exhaust has the right note, but creates a slight drone at cruising speeds under part throttle.
Acceleration from a standstill in the APR GTI shows a smooth power curve and linear delivery. The stage-three clutch and Quaife differential deliver power when and where it's needed. The quad-tip exhaust system is on the quiet side, but still has a nice deep tone.
H&R's GTI is equipped with a DSG transmission-a somewhat unfair advantage, since the computer does all the shifting. The Supersprint turbo-back exhaust is quiet, to the point where it's unnoticeable. If someone hadn't told us otherwise, we would have sworn it was stock.
A suspension system should inspire confidence. The ultimate configuration will allow a vehicle to excel at the track while maintaining a comfortable ride over even the most unfriendly freeway surface. The vehicle should not be so low that it inhibits daily use or aggressive cornering. The brakes should be quiet yet highly efficient.
The ABD GTI definitely qualifies as a daily driver. Ride quality is good and the vehicle handles well. The only complaint is with its steering. At low speeds it feels loose, disconnected and a little unpredictable. The Brembo brake kit, coupled with ABD's drilled rotors and lines, give a positive brake feel-great for the street as well as light track use.
The APR GTI has the most balanced suspension set-up. Its steering has a positive feel, offering crisp response. The overall ride is firm yet tolerable. The vehicle is a bit low, and with the tire and wheel set-up, aggressive cornering causes rubbing. Given the car's undeniable speed, the Alcon-based 13.5-inch front brake upgrade is only adequate.
The H&R GTI is a little on the firm side, but that can be remedied with easy access to compression and rebound damping adjustments. Even though the car is not equipped with the overly sticky Michelin Pilot Sport Cup tires found on its rivals, it maintains a neutral stance in every corner, with no over- or understeer. There is enough stopping ability to match the vehicle's power output, and the fact that it is DSG-equipped adds to the quality of the braking.