With the introduction of the K20Z3 engine, Honda again set the bar for normally aspirated four cylinder performance. The 2.0 liter K Motor pumps out an impressive 193.2hp and 141.4 ft. lbs. of torque (as measured on the Dynapack dyno).
Now, Moss Motors and Hondata have raised the bar yet again. 10psi of boost from the JR Gen IV supercharger and a custom Hondata tune up have created a tire smoking beast. Torque is increased by 27% and horsepower by 40%. While impressive, this doesn’t give the complete picture. Take a look at the dyno chart. Right around 2800rpm, torque (blue line) on the stock Civic Si is falling over and drops all the way to 6000rpm. Now look at the Supercharged Civic (red line). At 2800rpm, torque starts to rocket upward and climbs all the way to 6000rpm.
What does this mean? There is a profound difference in throttle response and acceleration. Power and torque are now available all the time, in every gear. First and Second gear shift comes fast and take your full attention to keep from banging against the rev limiter. Simply put, the Supercharged Civic Si transforms into a completely different car. Supercharged, the Civic Si becomes a tire smoking, tire shredding beast.
While horsepower and torque are important, drive-ability is key. Drive-ability refers to all the little things that are easily forgotten. Does it idle properly? Is acceleration smooth without hiccups? Can the engine be lugged at low rpm around town? Is it still capable of getting stock gas mileage? The answers to all of these questions are Yes, Yes, Yes and Yes. The annoying throttle hang (between shifts) from early Civic Si’s is gone. Simply put, drive-ability is perfect.
The JR Gen IV Supercharger is our proprietary external housing utilizing Eaton’s Gen IV rotating group. Integrated into the supercharger is a vacuum bypass system that allows the supercharger to free-wheel under light throttle conditions. This saves fuel and reduces parasitic loss on the engine. Under heavy throttle, the bypass valve closes and instant boost is achieved giving seamless acceleration and throttle response.
2006-2009 Civic Si Supercharger Specifications:

• 10psi of boost (at sea level with completely stock exhaust and Injen Cold Air Intake)
• VTEC starts at 3200rpm
• 8500 RPM Rev Limit
• Power up 78hp
• Torque up 52 ft. lbs.
• ECU easily reflashed (No Key or Immobilizer necessary)
• Bolt on installation, Completely reversible
• 2 year, 100K warranty
• Not CARB approved

Note: A small amount of material has to be removed from a bracket that's bolted to the block to mount the intake manifold. The block is not modified in any way. Please see page 9 of the instructions for full details.

Larger installed photo