Since the original Subaru engine layout is set up for all-wheel drive, JUN had to convert the car to FR layout by making a custom bell housing adapter for the Hollinger 6-speed sequential transmission. While the engine uses an Ogura Racing Clutch lightweight chromoly flywheel and clutch combo for the EJ25 Impreza for quicker revving, JUN had to fabricate a custom one-off drive shaft to connect the Hollinger tranny to the differential, which is actually a Skyline GT-R unit and a Cusco LSD installed inside the pumpkin.
JUN also customized the intercooler to fit the Impreza using a Trust core, then welded up custom intercooler piping, using 60-70mm pipe sections. The oil cooler chosen was also a Trust unit, with 16 rows to keep the car running cool at high rpms.
The radiator setup, however, is pretty different, and always amazes people the first time they lay eyes on the car. The radiator itself is a 3-row unit, which was special ordered from Yashio Factory in Saitama, which isn't too far from JUN. The engineers at JUN custom-mounted this Yashio radiator in the trunk of the Impreza since there wasn't much room left in the engine bay. To make this work, JUN had to cut the side of the car and add custom air scoops in the rear doors of the Impreza, which would use metal ducting to route air to the radiator while Kumakubo has the car sideways during a high-speed drift. Since JUN customized the M-Sports wide-body panels for the car, the rear fender scoops were originally twice as big, but when Kumakubo saw the huge intake scoops, he thought it looked a bit too bulky, and asked the mechanics at JUN to make it smaller. Since the customer is always right (especially when that customer is Nobushige Kumakubo), the JUN technicians reduced the size of the scoops and vents, and found that there were no problems with the water temperatures even though the scoops were smaller, so it seems the orange bear got his way after all. Other than the custom air scoops on the side of the car, the rest of the aero kit (front/rear bumpers, side skirts, hood, and fenders) was made by M-Sports, which is the same company who sponsors Kumakubo's close friend and Team Orange counterpart, Kazuhiro Tanaka. When I asked Kumakubo's chief track support mechanic, Igusa, why M-Sports chose to make only the Impreza's hood and front lip spoiler out of carbon kevlar, I was quickly corrected. "No, no, Antonio; it's not Kevlar. Technoora." I didn't understand. I thought he was teaching me the Japanese translation for Kevlar. "Nani? Wakaranai. What did you say? I don't understand," I responded. Igusa continued to explain that Kumakubo is sponsored by a company named Teijin, which makes this fabric product called Technoora, a strong fabric that's like carbon Kevlar, but is much stronger, lighter, handles impact better and is harder to break. Apparently, Kumakubo's yellow-hued hoods on his S13 K-truck, S15 Silvia, and WRX have all been made out of this new Technoora material. All the while, most of us thought it was some sort of carbon kevlar! Kumakubo seems to be the first person to use Technoora for automotive purposes, and innovated its use in motor sports.
For the rest of the chassis customizing, JUN fabricated a one-off chromoly roll cage and spot-welded areas of the interior, around the doors, engine bay, and trunk area. Kumakubo also asked that JUN install a set of air-jacks on the car, because he thinks the air jack systems on Super GT cars are so cool, not to mention convenient. Kumakubo didn't want to wait around all day for Igusa to manually jack up each end of the car. When he wants those tires changed, he wants it done ASAP. Everyone knows the key to control when drifting is a good suspension. For his footwork needs, Kei Office custom made a set of coilovers to match Kumakubo's spring rate and dampening specifications, using Swift springs and DG5 dampers. The rest of the Impreza's suspension components are pretty much all made by Cusco, from the under chassis bracing to the rear arms and pillow ball links. Even all the bushings on the car are pillow ball-type from Cusco. The only exception is the standard STi strut tower bar, which has a tow hook welded to it. This tow hook sticks out of the hood for ease of access.
Braking is an important part of drifting, when it comes to adjusting drift angle and driving line. To ensure the brakes would perform optimally, Kumakubo requested stainless steel brake lines and Endless brake pads to be installed on his standard OEM brake rotors and calipers. It just goes to show that huge brake rotors and 6-piston calipers aren't absolutely necessary for drifting, although it does make things easier sometimes. The car sits on wide Enkei RPF1s, with 255/40R17 Advan Neova tires mounted on the 17x9.5J front wheels, and 265/35R18 Neovas mounted on the 18x10.5J rear wheels.
Inside the cockpit, the Impreza is all business. The rear seat area was gutted and replaced with the huge ducts which lead from the rear doors to the rear mounted radiator. The only thing inside the car, aside from the custom made rollcage, are the bright red Bride bucket seats and Teamtech camlock seatbelts. Kumakubo installed a Key's Racing 350mm suede steering wheel with quick release hub, along with Stack gauges for instrumentation. To add to the Impreza's "rally look," JUN installed some rally style metal footplates on the floor of the car. While I was shooting photos of the car, Kumakubo asked if I wanted to go for a ride in the Impreza. Uhmm, let's see - how do you say, "Hellfockeryeah!" in Japanese? I've always wanted to ride with the Tsuisou King (Tsuisou meaning "tandem") himself on his own stomping grounds at Ebisu's Minami Course, where the D1 competition is held. As I strapped myself into the Bride buckets, I asked Kumakubo how he likes the Impreza in comparison to the Ichi-go (his famous S15 Silvia). Kumakubo smiled and explained that, "compared to the Ichi-go, the driver's position is different in the Impreza. It is more centered towards the middle of the car, further from the engine." Since his seating position is different, when he would drift the Impreza, he used to think that it had a lot more angle than it actually did. In fact, it took several of his friends watching his runs from outside the car to convince him that the angle was actually shallower than he thought. Kumakubo explained that this is a situation that is also common with the 350Z and G35. Now that he has been able to overcome this issue, he can now achieve a deeper angle in the Impreza than he ever could have gotten in his S15.
Riding with Kumakubo on his home court was awesome, to say the least. He blasted through the course full throttle, coming closer and closer to the pit wall, and then with a flick of the steering wheel, he would send the Impreza into what seemed like a violent left hand spin at over 160 kph (100 mph), but Kumakubo's mastery behind the wheel is unequaled. He deftly counter-steered to the right and feathered the throttle, controlling his ferocious orange Impreza at high speed, with a line so perfect that the left front tire would pass over the rumble strip every single time. We were not alone on the racetrack when Kumakubo took me for this ride along. There were about 15 cars out on the course, with a mix of S13s, S14s, AE86s, assorted Skylines, and Toyota Mark IIs. However, the less experienced drivers on the course couldn't help but be intimidated by the WRX's menacing HID headlights rapidly approaching in the rearview mirror, and while the gold and brown graphics depicting a ferocious grizzly bear on the side of the Impreza have a sort of "regal" look to them, the graphics also kind of screamed "get the hell out of the way" at the same time. One by one, the other cars on the track either nervously spun, or pulled to the side, bowing to the king as he passed. Amazing would be an understatement.