During our previous D-Spec experience using a variety of otherwise stock street cars (Minivans to Mustangs and everything in between), we found the D-Specs could be turned down to yield a limousine ride because stock spring rates are on the soft side to begin with. Turning the D-Specs toward hard really controlled the spring and gave a distinctly better handling ability, and the ride was still better than if high rate springs had been fitted. So, for most enthusiasts who daily drive their Mustangs to work, but want occasional back road glory, we figure a stock or close to stock spring with the D-Spec would be a great combination, if not the ultimate handler. For that, a sport spring and the D-Spec are required.
On the other hand, combined with the typical Mustang lowering spring, the D-Spec will give better control than the stock shock over the stiffer, shorter springs. Turning the D-Spec down will still give some relief on long cruises, rough roads, in the rain and so on.
One application where we see the D-Spec shining is with a street/strip car. Often fitted with 90/10 drag struts, these cars are uncomfortably floaty in street driving and approaching hopeless when driving with any enthusiasm in corners. Here, a D-Spec should prove ideal, as it could provide a truly soft dragstrip launch, and also be turned up for more than acceptable handling on the street, or even on open track day. It definitely has the adjustment range.
Of course, for any given spring rate, there is going to be a shock setting that works best, so the spring rate will still play a major role in where a Mustang will handle best.
The other D-Spec advantage is fine-tuning the shocks to a specific car's situation. Mustangs generally need a moderately firm front strut and soft rear shocks. The D-Specs allow you to best meet this need, and should you transfer the battery to the trunk, fit a huge stereo, install a fiberglass hood, and so on, the D-Specs will easily adapt to your chassis' needs.
We also found the D-Specs easy to adjust. The front struts use a small tool that can live on the keyfob, while the rears on Bud's car were fitted with prototype remote adjusters. The fronts don't need them, as the strut is front and center underhood, while the top of the rear shocks is sort of buried in the forward, top section of the trunk. The remote adjusters were simple lengths of hose with the adjusting tool permanently attached at the end. All that was necessary was to open the trunk, grab the hose and turn the knob. Tokico will offer these in snazzy stainless-steel-braid versions shortly.
D-Spec adjusters have no clicks or discrete stops, so the way to adjust them is to run them in all the way tight, then count turns as you unscrew the adjuster for increasing softness. The Mustang units are full soft after seven turns-so you don't have to spend all day twisting the knob. On Bud's car, we found three turns toward soft was our best compromise between ride and handling.
We spent plenty of time driving and playing with the shocks because the car was fun to drive. Those driving lights were particularly interesting as it's dark in our out-of-town location, so we can use powerful lights. Bud had the PIAA's wired and aimed for low-beam-only operation to avoid dazzling oncoming drivers and the better to see potholes and such in town. They threw an intense, daylight-like light, so we would have preferred them on with the high beams. But in the car's usual urban environment, they probably do best as low beams.
The seats helped in cornering, but are wide enough in the waist and shoulders to allow easy in and out maneuvering, and the Lunar gauges were a fun touch. We found them blindingly bright at night however, without enough dimming capability.