The Mustang RTR Spec 5 Is An 870 HP Pony Car That’s So Ready To Rock

By Gary Gastelu |

Sep 25, 2025

The Ford Mustang GTD has some competition … from inside the barn.

Ford Racing driver Vaughn Gittin Jr’s RTR Vehicles has revealed the 2026 Mustang RTR Spec 5, which is the most powerful car the performance tuning outfit has ever made.

The Spec 5 starts out as a Mustang GT with the factory performance pack, but its 5.0-liter V8 gets a 3.0-liter Whipple supercharger, intercooler and RTR-designed Borla cat-back exhaust that cranks it up from 480 hp to 870 hp.

That beats the GTD’s 815 hp 5.2-liter supercharged V8 by a wide margin. RTR offers it with the choice between a six-speed manual or a 10-speed automatic transmission. The GTD uses an eight-speed automated twin-clutch transmission and is not offered with a stick.

The Spect 5 isn’t just about power, however, RTR gave the suspension a full overhaul that’s nothing like a production Mustang’s. It’s been equipped with 30-way adjustable struts and dampers, height-adjustable springs and adjustable sway bars on both ends. The number of setup possibilities will make your brain hurt. The GTD gets its own even more radically redesigned suspension, but without the same level of adjustability.

Brembo brakes and two-piece rotors provide the stopping power for the Spec 5 and are tucked inside 20-inch RTR Aero 5 Evo forged wheels that are wrapped in 10.5-inch wide front, 11-inch wide rear Michelin Pilot Sport 4S Tires.

The body has been overhauled with RTR’s signature illuminated nostrils in the grille, composite widebody fenders with striking tire cooling vents, unique spoiler and carbon fiber front, side and rear splitters.

There’s a heavy helping of RTR badging and graphics outside and inside, including a serialized number plaque with Gittin’s signature, and Recaro seats with throwback ribbed leather upholstery.

“As RTR has evolved through the years, so has our design and engineering capabilities througgh special projects and motorsports learnings,” Gittin said. “Spec 5 doesn’t reference our peers – it’s derived from the core DNA of RTR. This Mustang embodies everything we stand for – confidence, capability, and our ‘Ready to Rock’ mindset.”

The price is $159,999 and just 50 will be offered for 2026. Yea, that’s a lot, but less than half what a $327,960 Mustang GTD goes for. RTR offers an endless array of standard and optional paint colors, however, including the iconic color-shifting Mystichrome, which tops the list at $15,000.