Unless you happen to own a dyno , accurately keeping track of which modifications benefit your vehicle may be a seat-of-the-pants operation. AEM is hoping to change that for people who are serious about wringing the absolute most out of their vehicle with the unfortunately-named Dyno-Shaft.While the product may sound like a bizarre fetish film, it has the potential to revolutionize tuning for those of us who don't have access to high-dollar engine evaluation equipment. The Dyno-Shaft uses grade-strain gauges to measure horsepower and torque at transmission output shaft, so AEM maintains that the system's readings aren't impacted by variables that typically skew accelerometer readings.AEM says that the the data broadcast device for the system is non-contact, doesn't use slip rings and needs no batteries, all of which are good things. Buyers simply install the supplied slip-yoke as well as a drive-shaft speed sensor and get going. Data is transmitted via a CAN-bus communications network to a data logger or an AEM engine management system. Prices start at $1,160.96 for cast-iron slip yolk applications, and AEM says that each Dyno-Shaft is specifically calibrated for your application. Chrome moly yolks are also available for higher-horsepower applications. We desperately want to play with one of these to see how accurate it is compared to a traditional full dyno setup.