PERRIN 16-19 Subaru Crosstrek / 04-11 Forester / 15-21 WRX STI Transmission Support (Manual Only)

Stop Transmission Slop Dead: The PSP-DRV-151 Fills the Factory Gap That Lets Your Manual Gearbox Float

Every Subaru running a manual transmission shares the same fundamental design flaw from the factory the OEM T-shaped transmission support insert fits loosely inside the rear transmission mount, leaving roughly 0.5 inches of clearance in all directions. That slack lets the back end of the transmission float, which softens shift feel, reduces drivetrain connection under acceleration, and accelerates wear on the mount itself.

The PERRIN PSP-DRV-151 transmission support is a direct-fit replacement insert machined to a larger profile that eliminates those gaps, reducing maximum deflection to 0.1 inches. The result is a firmer, more mechanically direct connection between the transmission and chassis, giving the driver more feedback at the shift lever and better power delivery through the drivetrain. PSP-DRV-151 is a manual-transmission-only application covering the 2016 to 2019 Subaru Crosstrek, 2004 to 2011 Subaru Forester, and 2015 to 2021 Subaru WRX STI on manual gearboxes.

Key Features

• Oversized T-shaped insert machined to fill the factory transmission mount gap, reducing deflection from 0.5 inches to a maximum of 0.1 inches
• Machined from 6061-T6 aircraft-grade aluminum for maximum strength-to-weight ratio
• Hard black anodized finish for corrosion resistance and surface durability under underhood heat and moisture
• Direct drop-in fit into the factory rear transmission mount receiver with no drilling, cutting, or modification required
• Improves shift feel and drivetrain connection by reducing transmission float during acceleration, braking, and gear changes
• Compatible with manual transmissions only: 2016-2019 Crosstrek, 2004-2011 Forester, 2015-2021 WRX STI
• Will add some NVH (noise, vibration, harshness) to the cabin, which most performance drivers find desirable as it signals a more solid drivetrain connection
• Designed and manufactured by PERRIN Performance in the USA

Fitment

Specifications

What's Included

• 1 x PERRIN PSP-DRV-151 transmission support insert
• Hardware for installation

About PERRIN Performance

PERRIN Performance is a Subaru-focused aftermarket manufacturer headquartered in Tualatin, Oregon, producing performance parts for street, track, and rally-inspired builds since 1997. Every PERRIN component is engineered and tested on actual Subaru platforms in real-world and track conditions before release. PERRIN is a direct-to-consumer and dealer brand with one of the broadest catalogs of Subaru-specific drivetrain, intake, suspension, and exterior components available in the US market. The PSP-DRV-151 is backed by the PERRIN Performance limited warranty against defects in materials and workmanship.

Frequently Asked Questions

Does the PERRIN PSP-DRV-151 fit the 2015-2021 WRX (non-STI) with a manual transmission?

The product title specifies WRX STI, but the PSP-DRV-151 may also fit WRX models from the same generation that share the same rear transmission mount design. Verify fitment with PERRIN Performance directly at perrin.com or call their tech line before ordering if your vehicle is a WRX rather than STI. The listing specifies STI fitment, so confirm compatibility before purchase.

Will the PSP-DRV-151 work with an automatic or CVT transmission Subaru?

No. The PSP-DRV-151 is explicitly designed for manual transmission vehicles only. Subaru models equipped with CVT or automatic transmissions use a different rear mount geometry and require the PERRIN PSP-DRV-161 (CVT/Automatic version) instead. Using the wrong support on an automatic transmission application will result in improper fitment.

How much noise or vibration does the PERRIN transmission support add?

The PSP-DRV-151 will introduce some additional NVH (noise, vibration, harshness) into the cabin, specifically low-frequency drivetrain vibration transmitted through the rear mount. For performance drivers, this typically manifests as a more connected, mechanical feel. For daily commute use, the added vibration is noticeable but generally not objectionable at highway speeds. Most buyers who install this product on a street-driven WRX STI or Crosstrek report the NVH increase is minor and acceptable given the shift feel improvement.

What tools are required to install the PSP-DRV-151?

Installation requires basic hand tools including a floor jack and jack stands, a 17mm socket, a 14mm socket, and a torque wrench. The factory transmission braces must be lowered to access and swap the rear transmission mount insert. Total installation time for an experienced home mechanic is approximately 45 minutes to 1 hour. PERRIN includes an installation guide with the part.

Is the PSP-DRV-151 legal in California under CARB regulations?

The PSP-DRV-151 is a mechanical drivetrain support and does not affect engine emissions systems or air intake pathways. It is not subject to CARB (California Air Resources Board) executive order requirements. However, as with all aftermarket performance parts, verify compliance with any applicable state or local regulations for your specific use case and vehicle.

How does the PERRIN PSP-DRV-151 compare to the factory transmission mount bushing replacement?

The factory approach to addressing rear transmission movement typically involves replacing worn rubber bushings in the transmission brace crossmember. The PSP-DRV-151 addresses a different issue: the gap between the T-shaped support insert and the mount receiver exists even when the rubber bushings are brand new. Both approaches address transmission movement but target different sources. For maximum drivetrain rigidity, some builders do both.

Does the PSP-DRV-151 fit the 2004-2011 Subaru Forester XT with a 5-speed manual?

The fitment range listed for the PSP-DRV-151 covers 2004-2011 Subaru Forester models with manual transmissions. Both naturally aspirated and turbocharged Forester XT variants from that generation that were equipped with manual gearboxes share the same rear transmission mount design. Confirm your specific model year and transmission type before ordering.

What is the warranty on the PERRIN PSP-DRV-151?

PERRIN Performance backs the PSP-DRV-151 with a limited warranty against defects in materials and workmanship. Warranty coverage addresses manufacturing defects such as machining errors, anodizing failures, or dimensional problems. It does not cover damage caused by improper installation, racing use, or normal wear. Contact PERRIN Performance directly at perrin.com for specific warranty terms and claim procedures.

Installation Instructions

1. Safely raise the vehicle onto jack stands rated for the vehicle weight. Never work under a vehicle supported only by a floor jack.
2. Support the rear of the transmission with a floor jack and a block of wood to prevent it from dropping when the transmission braces are removed.
3. Using a 17mm socket, remove the two bolts securing the rear transmission brace to the chassis on each side.
4. Using a 14mm socket, remove the additional smaller bolts if present on your specific application. Consult the PERRIN installation guide for bolt locations on your model year.
5. Lower the transmission slightly using the floor jack until the rear transmission mount and support insert are accessible.
6. Remove the factory T-shaped transmission support insert from the mount receiver by pulling it free from the rubber mount housing.
7. Install the PERRIN PSP-DRV-151 insert into the same mount receiver. The oversized profile will fit snugly with minimal clearance; this is correct and intended.
8. Raise the transmission back to its seated position, aligning the brace bolt holes with the chassis mounting points.
9. Reinstall the rear transmission brace bolts. Torque 17mm bolts to 103 ft-lbs and 14mm bolts to 51 ft-lbs per Subaru factory specification.
10. Remove the floor jack support from under the transmission and lower the vehicle from the jack stands.
11. Test drive to confirm no unusual noises and to verify smooth gear engagement through all gears.