JDM Close Ratio 5th and 6th Plus Synchro Up-Grade (6MT)

JDM Close Ratio 5th and 6th Plus Synchro Up-Grade (6MT)


This kit includes a new 5th and 6th gear for the 6-Speed transmission that came in the USDM STI, and new Carbon Synchros (baulk rings)for 4th, 5th and 6th gear.

The new ratios for 5th and 6th gear are:

  • 5th - 1.062
  • 6th - .842

This will help turn your STI transmission into a close ratio gear box, and improveshifting between 4th, 5th, and 6th gear. Use to improve on problematic 4th, 5th, 6th synchro performance. This kit also converts your USDM/Euro gearbox to proper Group N ratios.

Professional installation is very strongly recommended. This part is considered for race use, and therefor does not have a parts warranty.

warning_symbolWARNING: Operating, servicing and maintaining a passenger vehicle or off-road vehicle can expose you to chemicals including engine exhaust, carbon monoxide, phthalates, and lead, which are known to the State of California to cause cancer and birth defects or other reproductive harm. To minimize exposure, avoid breathing exhaust, do not idle the engine except as necessary, service your vehicle in a well-ventilated area and wear gloves or wash your hands frequently when servicing your vehicle. For more information go to https://www.P65Warnings.ca.gov/passenger-vehicle.

More Information
Product Type Drivetrain
Drivetrain Gear Sets, Transmissions, Differentials
Brand Subaru JDM
Need Help with this product?

Chat with our staff using our Live Chat, Call us at 303.402.5142 or Email us at

Fast Shipping

Products ship within 2 days.

Easy Returns

Friendly return policy because our priority is making sure you have the right product.

Safe and Secure Shopping
click here