There's a comprehensive new upgrade available for the Mustang that promises results like nothing currently on the road.White sports car front side with neon green wheel and yellow-accented splitter on asphalt.If you buy from a link, we may earn a commission. Learn moreBetween its Exclusive Manufaktur and Sonderwunsch programs, Porsche offers customization geared to enthusiasts of all tastes and ambitions. No matter if you're after a unique 911 paint job or a striking Carrera GT overhaul, the brand can make it happen.AdvertisementAdvertisementOf course, this kind of treatment does come at a premium. Beyond their outright expense, such projects often come with a multi-year waitlist and require a significant investment of patience.Thankfully, there are more immediate and accessible ways to scratch that bespoke performance itch. In fact, if you're looking for serious personalization, the answer may actually lie in America's pony car. RTR is offering its Signature Package as an upgrade option for existing owners of Spec 2 and Spec 3 Mustang builds. - Credit: RTRYour signature RTR MustangSpecifically, the new Signature Package that RTR has cooked up for its Ford Mustang tunes. While it requires pairing with a Spec 2 or Spec 3 car (more on that later), it nevertheless unlocks some comprehensive options.Accordingly, as part of the Signature treatment, the RTR team begins with a one-on-one design consultation to refine the creative vision. From there, the finalized colors and livery choices are applied across a curated mix of visual touches.The treatment includes eye-catching touches like LED accents for the intakes.. - Credit: RTRBeyond a litany of custom RTR badge color options and a set of graphics designed at the RTR Studio, the Signature Package includes additions like LED air intakes and powder-coated wheels. Furthermore, along with the mirror caps, buyers can specify the color of aero elements such as the front splitter, side skirts and rear diffuser.AdvertisementAdvertisementAs if those appearance changes weren't enough, the Signature Package does bring a few choice tweaks that help further refine Spec 2 and Spec 3 builds. The suspension benefits from Tactical Performance coilovers, and the package also includes a Borla cat-back exhaust setup. If the Spec 3's 810-horsepower output isn't enough, RTR's Signature Package can add still more to the output. - Credit: RTRWhat's more, assuming the Spec 3 doesn't already bring enough power, RTR offers a Whipple Stage 2 Upgrade Kit that raises output to a total of 870 horsepower. For perspective, that's a figure that even outguns the most powerful Mustang Ford builds, the Nurburgring-slaying GTD.Undercutting Ford's optionsToward that end, the value of the RTR Signature Package really comes into focus when you consider Ford's own Porsche-spirited customization opportunities.Buyers work with the RTR design team to ensure that their proposed visuals make for a cohesive design. - Credit: RTRIt may be an option that's only available to existing Spec 2 and Spec 3 owners, but it still makes serious Mustang personalization more accessible to the masses.AdvertisementAdvertisementThat's because, even when you add up the price of a new 2026 GT, a tuning package (the former starts from $18,995, while the latter adds $33,995 or more) and the $12,500 of the Signature treatment, you can still come out with a heavily upgraded and more powerful Mustang for less than something from the Blue Oval. After all, much as Ford's new Dark Horse SC seems like the natural alternative, it quickly becomes a pricier option. MSRP for the up-spec Mustang might start at a fairly comparable $108,485, but adding appearance and performance upgrades like the Track Package can bring that total to $144,985 or higher.While they don't bring factory Blue Oval pedigree, RTR's tuning packages nevertheless make for some impactful upgrades. - Credit: RTRThe Mustang GTD is an even more unattainable option. As the brand's halo performance car, it's a vehicle on a completely different order of magnitude, not only costing in excess of $300,000 but also requiring prospective owners to fill out applications during limited purchase windows.An RTR might not deliver the same factory pedigree or engineering as these Blue Oval grails, then, but the Spec 2 and Spec 3 treatments still amount to thorough overhauls. They already brought bodywork changes, suspension tweaks and power mods, and the availability of truly unique looks should only serve to entice more creative buyers.If you're looking to design a Mustang that'll turn heads, RTR may have the answer. - Credit: RTRAvailability and pricingRTR's Signature Package is available to existing Spec 2 or Spec 3 owners of 2024 and newer Mustangs, starting from $12,500.AdvertisementAdvertisementIf you're interested in one of those treatments, they start from $18,995 and $33,995, respectively.White sports car with neon green accents and wheels parked in front of a black building with a large "RTR" logo.2026 Ford Mustang RTR Signature Package Starts at $12,500 About the Author: Gray is an associate editor at Gear Patrol, covering cars, motorcycles and anything else with wheels. When he's not chasing the latest industry news, he's probably wrenching on one of many projects. For better or worse, he believes classics make perfectly practical daily drivers.Want to stay up to date on the latest product news and releases? Add Gear Patrol as a preferred source to ensure our independent journalism makes it to the top of your Google search results.add as a preferred source on google