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Sonnax

No one knows transmissions & torque converters like 2008-sonnax-logo-white

Line Pressure Booster Kit

Get a Boost with Sonnax Line Pressure Booster Kits

Affordable Kit for Big Performance without a Big Price Tag

The larger boost valves and stronger PR springs in Sonnax booster kits raise line pressure the SMART way by controlling pressure increase progressively with the demand of driving conditions.


  • Simple, affordable parts require no special tools or reaming to install.
  • Slightly stronger springs provide a modest base line pressure increase. Unlike other, stronger aftermarket springs, Sonnax springs won't overload the pump at idle.
  • Larger boost valves deliver demand-based line rise without low-speed harshness.

How Progressive Boost Works:

The combination of Sonnax booster kit valves and springs gives you the best of both worlds: a modest pressure increase at the low end, with a high-end pressure that is equal to or greater than that of other aftermarket kit springs.

The combination of boost valves and springs is the ONLY way to progressively increase line pressure.


Check out these other great Sonnax transmission kits:

Graph showing the long term effectiveness of Sonnax Line Pressure Booster Kits
  • We used the 4T65E-LB1 in several applications...it doesn't give harsh shifts, just a little something extra. Very nice product and I highly recommend it."

    D. Tucker
    Tucker's Transmission
    Pine Bluff, AZ

  • Use the Sonnax 4L60E-LB1 progressive boost valve...it will put a smile on your customer's face."

    D. Stewart
    Dan's Service Center
    Cliff, NM

  • I just received my line pressure booster for my 2012 Ram and wow! The CPU gets the new pressure signal very fast...30 seconds of slow-medium driving...and when I floor it....yihaaa! It shifts aggressively and I can feel the tranny grab the clutches with more power when it changes gear...great product! Thumbs up!!!"

    J. Martel
    Senneterre, Québec, Canada

12 Booster Kits

Sonnax Hydraulic Booster Kits


Sonnax Electronic Booster Kits

68RFE 45RFE, 545RFE

Sonnax electronic line pressure booster kits modify the sensor signal which causes the computer to create a pressure increase. The booster kits 44957-LB1 (10-15 psi increase) and 44957-LB2 (15-30 psi increase) are installed between the pressure sensor and vehicle harness using OE-style sealed connectors and do not require any modification or changes to the transmission. Simply unplug the vehicle harness and reconnect with one of these kits in line.