“Run” refers to increased engine performance. You can easily overpower a chassis and make a motorcycle almost un-rideable, therefore power characteristics on a 450 are monumental. It was an important goal of the Suzuki engineers to produce more power while still maintaining rideability and control. The current (2017) RM-Z450 engine is good, so Suzuki engineers didn't abandon their current engine design. Instead they refined and improved on what they currently have. Most of the focus was on the engine's efficiency. First they looked at the cylinder head where they were able to redesign the intake port, increasing tumble flow by 25%. Naturally, the new intake port design is going to need more air, so Suzuki complimented this change with a new and much larger air filter aperture. The larger aperture also has a new air boot, helping increase air flow from the air filter. These changes are designed to increase peak power, while also maintaining low-to-mid range power. Updated camshaft profiles are designed to help increase power at all engine speeds. The rider’s ability to control this additional power is managed through a Mikuni throttle body featuring an inverted fuel injector. With an inverted fuel injector, the fuel is released upward and bounces off the throttle body butterfly valve in an effort to increase fuel atomization along with throttle response. This is a design Suzuki has been using on their GSX-R 1000 from as far back as 2000. The fuel pump has been updated with a higher pressure model in an effort to improve throttle response and keep up with the additional air flow. Now that the engine was set to be able to get more air/fuel, in it was going to need to be able to handle the extra pressure. Suzuki went to a "rib," or boxed-in, design piston to get the most power out of this new intake system and also offer improved durability.