ACT HD-M/Performance Street Sprung Clutch Kit – 04-21 STI / 07-09 Spec B LGT


ACT HD-M/Performance Street Sprung Clutch Kit – 04-21 STI / 07-09 Spec B LGT


This kit features  ACT’s most popular Heavy Duty pressure plate and most popular street disc. It has a Torque Capacity of 522 ft/lbs.


In stock



ACT Clutch Kits stand unequaled in terms of consistent pedal feel, high torque capacity, long wear life and durability. In-house manufacturing is critical in tuning components specifically to each individual application, while maintaining the predictable ACT pedal feel across the entire catalog.

ACT’s Performance street discs feature premium organic materials with higher copper content for better heat transfer and steel-backed lining for greater burst strength and durability. ACT Heavy Duty pressure plates use exclusive diaphragm design to increase clamp load, reduce deflection and maximize clutch life. All diaphragms endure a four-stage, heat-treating process for unparalleled performance. ACT pressure plates have precision cover stampings to provide rigidity and consistency. CT’s Performance street discs feature a reduced marcel for faster shift action to complement ACT pressure plates. Quiet operation with increased strength and reliability.

Monoloc is a one-piece, direct replacement or upgrade to the standard, two-piece wedge collar and wire ring featured in pull-type clutches. The spring tension of the segmented retaining ring is carefully calculated and tested for optimal performance. It provides uniform loading on the bearing and pressure plate to assure proper alignment, regardless of driver influence or vehicle modifications. Monoloc’s hardened chrome-moly steel construction will provide years of service.

Quick Specs

  • Disc Material – Organic
  • Torque Capacity – 522ft/lbs
  • Torque Capacity over OE 45%
  • 9.4″ Disk
  • Feel – Light to moderate pedal effort, smooth positive engagement, OE to mild gear rattle, confidence during hard shifts
  • Recommend use – Street and race

Included in Kit

  • Performance Street Sprung Disk – 3000503
  • Heavy Duty Pressure Plate – SB019
  • Release Bearing– RB601
  • Pilot Bearing – PB1004
  • Alignment Tool – AT90
  • ACT Monolock Color

Recommended Break In Process

For organic street discs, ACT recommend breaking in the clutch for 300-500 miles with mild engagement, such as stop-and-go city driving prior to racing or spirited driving. ACT race discs usually only require a few hard slips to lap in the surfaces prior to normal driving or racing. Do not overheat the clutch during the break in period, as this can result in friction surfaces fusing together, hot spots, and friction surface glazing.


Additional Information

Weight19.8 lbs
Dimensions13.7 × 13.1 × 5.2 in


  • 2004-2021 STI
  • 2007-2009 Spec B LGT


Installation Guide

Install Guide

Install Video Guide