It's hard to believe that as of 2023, our original “RR625” ISF supercharger kit (that was later upgraded to RR780 with Stage 4), featured on many dozens of ISF’s throughout the world, has now been in production for over 6 years! While this kit has proven to be reliable and upgradable to power levels of over 700whp (or 800+hp at the crank), we are now introducing the Street kit intended to fulfill the needs of ISF owners looking for a significant power boost at a reduced price. This kit makes 550whp (about 625hp at the crank) with 30% ethanol blend (please refer to the dyno chart in the photo gallery).

Our new affordable RR625 Street kit features some of the same components as the RR780 kit such as the Rotrex C38-92 blower. We reduced the cost in the following way (please also refer to the comparison table below):

• Front Mount Intercooler removed. We are able to do this by reducing boost level a bit, and requiring the use fuel of 30% ethanol blend. Keep in mind, at peak boost levels of around 5psi, the minimal increase in intake air temperature is mitigated by using higher octane fuel.
• Dual Turbosmart Big Bubba blow off valves (BOV) replaced with a single BOV.
• Billet tensioner replaced with lower cost conventional heavy duty tensioner.
• ATI aluminum harmonically dampened crank pulley is replaced with a modified OEM pulley.

Please note that RR Racing is now using Rotrex C38R superchargers on all RR780 kits and C38-92 on this RR625 Street kit.

All these changes result in a kit that still delivers significant dyno proven power gains (530whp) at a reasonable cost!

Please note that this kit requires either a Methanol or Ethanol kits as an option for an extra charge (see options).

Also, all parts of this kit can be upgraded in the future, depending on power goals.