We're doing more than 180mph down a tight freight corridor when he says it: 57 seconds. The car we're in is an R32 Nissan Skyline GT-R, modified by Pentroof, a shop in Japan notorious for power tuning such turbocharged machinery as the Z32 Fairlady (300ZX), Silvia, GT-R and Legacy. The driver is none other than Mr. Kitabayashi, CEO and head of Pentroof. We quickly gather our thoughts as Kitabayashi continues to bury his foot into the throttle (aiming for 57 seconds?). Was this lap time set on the short course at Fuji Speedway? Or maybe at Ebisu or Nikko? No, 57 seconds is Kitabayashi's goal at the holy grail of all tuner racetracks: Tsukuba Circuit.
Filled with choppy corners and short straights, Tsukuba has become the benchmark track for the Japanese tuning market. Many shops and manufacturers bring their machines to the remote circuit, hoping to turn in the fastest lap time they can. Declaring one minute there is respectable, but 57 seconds is bold.
In the desolate land adjacent to Tokyo's Haneda Airport stands the turn-around point for our blast in the Pentroof GT-R. The end of the freight tunnel becomes an impromptu pit stop and permits another conversation with our host and pilot. And there is truly something to talk about with this R32 GT-R. Although it makes an estimated 700bhp and roughly 580lb-ft of torque, this Skyline is completely street legal.
Kitabayashi has decided to enter this R32 into the ST class of time attack competition. While the rest of the world focuses on trailered-in, carbon-bodied, radiator-in-the-rear, purpose-built track sluts, the ST class has to conform and pass shakken (pronounced: shah ken) regulation testing. Much like California's ultra-strict smog testing, shakken occurs every two years of a car's life and is a mandatory test to maintain ownership of a vehicle with over 250cc of engine displacement.
Generally costing at least $1000 (not counting any applicable repair costs), shakken consists of headlight, bodywork, speedometer, suspension and brake inspection, as well as a smog check. Anything deemed not up to standard must be repaired and re-tested before the vehicle can pass and be driven on public roads. Although items such as roll cages, coilovers, bucket seats, body kits and aftermarket exhausts are legal by shakken standards, they must still follow certain regulations concerning size, shape, noise and ride height. Contrary to the US tuning market, many Japanese parts manufacturers attempt to produce go-fast items that can pass government safety test procedures.
Another side effect of shakken is that those who aren't willing or able to shell out for the test, or its resulting repairs, will often sell their car and buy another that can pass. Many of these second-hand cast-offs are ultimately exported to other countries for use as spare parts. Any reader who has purchased a low-cost JDM SR20DET or B-series engine has the shakken program to thank.
Passing shakken regulations also means that, although the Pentroof GT-R produces power and poise in excess of the factory-built, 500bhp, limited-edition R34 GT-R Z-tune, this R32 is still roadworthy and is repeatable if Vehicle Inspection Association (VIA) pre-approved parts are used. Similar to US emissions regulations, shakken is most strict in the area of engine modification. All parts on this R32 comply with the law. Twin HKS GT-RS impellers heave 22psi into the Nismo throttle body, just downstream of the HKS dual-core front-mount intercooler. A Pentroof throttle body spacer was also installed to give a bit of swirl before the pressurized air enters the OE plenum.