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Makin’ Noise and Power—Granatelli Motor Sports Exhaust Cutouts

Posted By: Evan J. Smith
Makin’ Noise and Power—Granatelli Motor Sports Exhaust Cutouts
By Evan J. Smith
Widely known in the performance industry, Granatelli Motor Sports offers a host of performance parts and systems for most modern cars and trucks. The Granatelli name dates back to the early days of racing, with a history that rooted deep in many forms of motorsports including Indy Car, land speed racing, drag racing and more.
“Everyday I get up early and go to work and I'm excited,” said J.R. Granatelli, owner of GMS. “I’m Excited about the opportunity to continue the performance legacy that is part of the racing Granatelli's. Many of you reading this may not be old enough to remember STP Oil Treatment, Tune-up Masters, factory Shelby Mustangs with Paxton superchargers, land speed record setting twin Paxton supercharged Avanti’s or the famous Paxton Products/STP Novi Turbine Indy cars. The Granatelli’s had something to do with all of that and more. My father, Joe Granatelli, Sr. of the three more famous racing Granatelli brothers (Joe, Vince and flamboyant Andy), was chief mechanic for the Indy team and president of Paxton Products,” JR added, who is an accomplished businessman and racer.
We also spoke to J.R. about his line of products, namely the exhaust cut out and the GMS Slip-Fit and weld-in Electronic Exhaust Cutout Kits. GMS offers a variety of these kits, some with and some without the electric motor used to control opening and closing the system from inside the car with the flip of a switch.
“The gains from opening the exhaust are predicated on the combination and where you plan to go with your modifications,” he told us. “On a boosted Coyote we went from 560 rear-wheel horsepower to 582 RWHP for a 22-horsepower gain at the wheels. You wouldn’t expect that much on a naturally aspirated vehicle.” J.R. also mentioned the system picked up 18 horsepower on a stock Dodge Challenger Hellcat.
Kits are offered in Stainless steel, mild steel oval and with or without remote switches. There’s also a wide range of exhaust pipe diameters available. Complete Stainless systems include CNC-machined 6061 Aircraft Quality Aluminum Body Construction, "Smart Chip" Controlled Motor, "One Touch" Operation Rocker Switch and there’s no more needing to hold the switch, which usually damages internal gears. It has a Stainless steel butterfly plate and blade shafts, and unique V-band clamp allows turndowns to be rotated 360 degrees for ultimate adjustability. With other systems you may be limited to two or three clocking locations.
Polished Stainless steel turndowns offer 45-degrees slanted discharge angle
And the high-torque DC gear-reduction-driven motor insures total open and total closed operation every time. Lastly, drive gears are made of high-temperature carbon steel. Lastly, the system includes easy-to-use electrical connectors with heat-shrink wrapping for weather protection. You can learn more at

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