Project 2006 Subaru Impreza WRX

All Types Of Bars
Unlike some Japanese suspension tuners, who increase roll stiffness by just using kidney-busting springs, Whiteline shares the same mentality as many American tuners (and probably similarly rough roads). The G4 kit anticipates the use of anti-roll bars. While Whiteline also makes an entire line of adjustable anti-roll bars, beefed-up endlinks and anti-roll bar mounts, we went with a set of 22mm front-and-rear chromoly Sustec Stabilizers from Tanabe.

The idea (on a street car) is that most people don't want to get underneath to make adjustments. We also wanted a predictable balance of front and rear roll rates that didn't set the car into a spin on the interchange if you had to lift and brake for traffic, or lift the inside rear wheel up over every driveway. The WRX bars were designed for 2004 models, but we didn't have any fitting issues on our '06, nor did the bars bind against the stock end-links at our ride height.

We also added front-and-rear strut tower braces to make sure the suspension does the work, not the chassis. Although we're usually skeptical about the effectiveness of strut tower braces, especially on super-stiff modern chassis, we've never been able to come up with a test accurate enough to measure the change in chassis deflection. The DC Sports titanium pieces we added did make a difference we could see in terms of more front tire shoulder wear during extreme cornering. Part of why it works so well is that the non-hinged single piece design doesn't have an added degree of rotational freedom between the mounts and the actual bar that transfers the load. At a weight penalty of only 2.7 pounds in front and 1.6 pounds in back, it wasn't something we'd sweat.

DC's rear bar is designed in three pieces so it can be installed and neatly tucked behind the seat without any cutting. Two aircraft-quality bolts and fittings prevent rotation through the joints. The two main bars are tied together with a dimple-die reinforcement plate.

DC's rear bar is designed in three pieces so it can be installed and neatly tucked behind

Testing Month
You can imagine how many tires we'd be able to test in one month if we weren't SCC. But to us, getting a true street tire impression isn't just a matter of putting on a bunch of new tires during one long day at the track and banging out performance numbers. It actually has more to do with spending time on the street to learn all the little things you'd never notice while flogging it on track. So we got through just one set, the Maxxis MA-Z1 Victra UHP tire.

To make the test fair, the people at Discount Tire Direct supplied us with two sets of 17x7 Enkei J10 wheels with a +38mm offset, chosen because they can mount the same-size tires as stock. The original 215/45/17 Bridgestone RE92 tires were re-mounted onto one set, while the identically sized Maxxis MA-Z1s were mounted onto the other, so we could baseline the stock tire against the test tire on the same day under the same conditions.

We also came across a pressure-sensitive film made by Sensor Products Inc. and used that to get a contact patch for each tire. The Pressurex Pre-Scale Pressure Indicating Film is basically a sheet of material placed between two touching surfaces. Once there is pressure, the film will leave an impression of the contact. It sounds like an expensive way to get an impression of a contact patch, but Pressurex actually has a lot of applications for automotive use, ranging from brake pads to manifolds. Once an imprint is made, the film can be sent back to Sensor Products for post-processing that can break down pressure distribution so you can see how much pressure is acting on which spot and just how uniform it really is.

Even though Tanabe's 22mm chromoly Sustec anti-roll bars don't offer all the adjustable bells and whistles, they're light and compact with solid end mountings that don't have interference issues when lowering the car.

Even though Tanabe's 22mm chromoly Sustec anti-roll bars don't offer all the adjustable be

Stock Bridgestone RE92
The worn stock RE92s blew us away once we made the suspension changes. We didn't think showroom stock tires could work this well, especially when you look at the decidedly un-sporty tread pattern. But the technology and development time spent on the RE92s is clear. The tire is quiet, decent in steering response, communicates wheel motion well, and has a progressive breakaway limit.

Maxxis MA-Z1 Victra
One look at the Maxxis MA-Z1 makes several things apparent. The shoulder blocks are larger, which should mean more cornering grip, and the center V-tread pattern is set at an aggressive angle, which helps with water evacuation. Tread grooves are deep and cut at 90-degree angles, which hold more water, but have more tread squirm and scaling issues under intense heat.

This is exactly what we felt on the street and the track. Although the MA-Z1s physically generated more grip, they're as loud as some R-compound tires at highway speeds, had mild groove tracking characteristics, didn't communicate well how close to or past the limit of grip we were, and had some steering vagueness in the first couple degrees of turn-in. We think these traits were concessions made by the manufacturer for increased wet performance, which we didn't get the chance to test, except at the car wash. We also noted a shorter sidewall on the Bridgestones, even though both tires were the same size, which added to the steering and suspension edge while the car was on the RE92s.

We chose two identical sets of 17x7 Enkei J10 wheels for our tire testing. Stock reference tires and new test tires were mounted and taken to the track for back-to-back testing.

We chose two identical sets of 17x7 Enkei J10 wheels for our tire testing. Stock reference

Our figure-eight and skidpad numbers give an idea of the hairs we're splitting here. While none of the configurations even broke 0.9g or posted eye-popping times, the end result is that the combination of a Whiteline/Tanabe suspension, Maxxis street tires and wide torque band puts our 2006 Project WRX at the top of the list for the best street project car in terms of fun, driveability, durability, practicality, civility and just about anything else that matters in a car you'll be commuting in.