Each car also has the benefit of a top-dollar Bosch ECU and ignition system for complete tunability and data logging. Bosch also supplies the fuel pumps for all three race cars, as well as the fuel injectors for both the C6.R and the CTS-V. The race cars' owner and builder, Pratt & Miller, fabricated the custom headers and exhaust. Though they were tight-lipped about the specs on the C6.R's headers, they did say it runs straight-through glasspack-style mufflers with no crossover to meet the 105-108db noise restriction at some of the tracks it races. A very similar setup is run on the other two cars to allow exhaust to exit just under the doors. Pratt & Miller divulged that the headers on the CTS-V and GXP.R were made from 321 stainless steel and use a 4-into-1-style collector with 1.75-inch primaries on the GXP.R. (CTS-V specs undisclosed.)
Believe it or not, a Tremec T-56 sits behind the CTS-V's race-prepped LS2. It even keeps the stock-style H-pattern shifter, though the internals have been beefed up and outfitted with a road-race-friendly gear set. The CTS-V uses a 3.5-inch aluminum driveshaft and Tilton heavy-duty clutch to engage an upgraded IRS Getrag limited slip differential using a 3.91 or 4.11 gear (depending on the track). The Corvette, on the other hand, is allowed a sturdy front-to-back inline shifted Xtrac six-speed transaxle with a limited slip from Salisbury. Rearend gear varies greatly from track to track as with the GXP.R, which also employs an Xtrac transaxle with a similar design-though it uses a five-speed gearbox. Carbon clutches from AP Racing and custom carbon fiber driveshafts unite the Gen IV powertrains to the transaxles.
Similarities among the different race cars continue into the suspension setups, though they start to dissipate on the topic of chassis. The GXP.R, for example, rides on a complete tube chassis wrapped in carbon fiber, whereas the Corvette and CTS-V are full body cars that started as body-in-white shells. While class rules didn't prevent Pratt & Miller and GM from converting the front-wheel-drive V-6 coupe to a rear-wheel-drive IRS V-8-powered race car, it kept a tight leash on the construction of the Prep 2 chassis. The roof height, minimum ride height, and factory-appearing fasciae made improving aerodynamics a challenge. Thankfully, the fenders were allowed to be widened to fit lightweight 18x11.5-inch Forgeline three-piece wheels and meaty Hoosier 295/660R18 and 295/675R18 rubber. A four-wheel independent suspension setup with coilovers is used, as is on the CTS-V and Corvette, however the unique chassis changed the geometry of the fabricated components. In addition, class rules required the use of a front spindle and upright similar to NASCAR, which is made of stock car products. The rear spindle and upright is made of machined billet aluminum. AP Racing four-piston front and rear brakes enable late braking and keep fade at bay lap after lap.