Whiteline S550 Ford Mustang – Introduction and Initial Testing


After cutting, the exhaust pipes are cleaned up to remove burrs with a flat mill file in anticipation of installing the slip joints the Roush axle back kit uses to connect the Roush mufflers to the stock exhaust.


The Roush mufflers are slipped over the cut ends of the stock exhaust and are held in place with the provided stainless steel pipe clamps. The Roush muffler hangers slide right in place on to the stock rubber mounts. With the clamps loose, the mufflers are clocked so they are oriented properly with the rear bumper fascia.


Once the mufflers are in the correct position, the clamps are tightened down.


The final installation step for the Roush axle back system is to align the supplied flash-chromed dual wall tips. Dual wall tips are cool because they won’t discolor from heat.

There’s not much power to be gained, if any, from axle back upgrades at this point in the car’s engine modification cycle because the stock exhaust is pretty decent to begin with. The Roush exhaust is definitely louder now, but not obnoxious.

It has a deep low rumble at idle and sounds “buff” at WOT as the engines RPM climb. With more mods in the future, the lower backpressure of the straight through Roush mufflers might start to contribute towards power gains.

Next, Whiteline did a mild brake upgrade on the Mustang. With a 4 piston caliper and a 14″ rotor on the stock front brakes, the Mustang was pretty well equipped from the factory.  To keep things simple for consistency when testing new suspension components, Whiteline wanted to keep things pretty close to factory original so the cars original brake bias and stability control would not be affected while the suspension was getting changed around. For this reason, the stock brake pads were retained for now.


The 2017 S550 GT Mustang comes with some pretty big brakes from the factory. Front brakes consist of 14″ front brake rotors with 4-piston calipers.


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