For the past several years, ROUSH Performance has been on a roll with their RS series of cars. Beginning with the Stage 1 (RS1) that is mostly an appearance package, and going up to the Stage 3 (RS3) which offers near super car levels of performance, in a package with many enhancements.

A few weeks ago, ROUSH released the details on the 2015 RS1 and RS2 models, including information that the EcoBoost and V6 Mustangs would be available with the RS1 package. What we’ve been anxiously waiting for are the details and specs on the 2015 RS3. At the SEMA show this week, we finally got those.

ROUSH launched the 2015 RS3 and with a party Tuesday night featuring Justin Pawlak and Michael Essa. We caught up with them to get the full details on what appears to be the best RS3 ever.

Exterior

From the outside, the RS3 looks very similar to its other ROUSH siblings. The body work features significant upgrades and OE fit and finish. While it may look like just an appearance package, ROUSH representative Luke Macinnes says there’s much more to it. “It’s a brand new front fascia that we developed with corner pockets that feature aero ducts. New upper and lower high flow grills finish out the front. The sides feature new splitters, and a traditional ROUSH rear deck spoiler.”

Macinnes says that ROUSH worked closely with Ford’s aero team. They wanted to create a package that not only looked good, but was also aerodynamically functional and beneficial to the car. What they came up with not only looks fantastic, but according to Macinnes also improves airflow.

Suspension

Standard on the RS3 will be ROUSH single adjustable coil-overs, with optional three-way upgrade available. ROUSH Quicksilver wheels with Cooper UHP RS3 tires for some super sticky grip are also standard here.

Inside

Seating options will range from stock, to ROUSH upgrades with leather, custom stitching and premium materials. ROUSH gauges are also another option to let owners keep a closer eye on how their RS3 is operating.

Under The Hood

All of the exterior, interior, and suspension enhancements are fantastic, but what everyone really wants to know is about the engine. ROUSH has done significant redesign work on the housing for their Eaton TVS 2.3 based supercharger. This redesign improves the airflow to the supercharger even with the same twin 60mm throttle body that was used for the 2014 model. This results in the supercharger being able to pull a larger volume of air in, without increasing boost pressure. The final product is quite a bit more power over the previous generation RS3 that was based on the S197 chassis.

Macinnes said that engineers at ROUSH also had to look closely at the fitment of the supercharger housing to ensure it would have adequate hood clearance in the new S550 chassis. “We had to shave a little bit here and there to get the clearance we need, and what we feel is adequate for engine movement in a street car.”

The result of all this work is an engine producing 627 hp and 530 ft-lbs of torque at the flywheel. For the record, that’s a 52 hp gain over the 2014 RS3, and actually puts the standard RS3 on par with last year’s RS3 Phase 2, which featured a host of upgrades to bump power to this level.

Selectable Active Exhaust

We highlighted ROUSH’s upcoming variable exhaust technology in another story. This system will be an option on the RS3, and allow driver’s to select the amount of sound they want at the exhaust, or set it to automatic mode for predetermined exhaust performance.

Essentially the active exhaust system allows owners to run their cars nearly as quiet as stock, or open the system up at the touch of a switch to be loud and rowdy.

Challenges

With any new platform there’s always challenges to developing it and bringing it to market. Macinnes says the cowl bracing on the 2015 engine compartment presented a few challenges to making the supercharger system work. ROUSH is also presently awaiting CARB certification on the RS3 components so that they can begin selling the car.

Upgrades Down The Road

We asked if ROUSH has plans to offer Phase 2 and Phase 3 upgrade options for the RS3 in the future. In the past these upgrades have made staggering horsepower, and offered the ultimate in late model Mustang performance off the showroom floor. Macinnes acknowledges that as ROUSH engineers have more time with the cars, these types of upgrades and options will likely become available at a later date, but right now they can’t specify when.

Pricing hasn’t been finalized as of this writing for the RS3. If you can’t afford the window sticker, ROUSH Performance will also offer all of the parts and pieces to transform your own 2015 Mustang GT into whatever level ROUSH you’d like through their authorized dealer network.

We’ll be getting our hands on a RS3 to test in the near future, and as soon as we do we’ll bring you a full report on how it performs, and what we think once we spend time with it. Until then, enjoy the photos and information on the car.