String Theory Garage, in conjunction with JCR-Developments and Eibach, has developed an adjustable-height performance spring kit for the Toyota GR Yaris designed to work with standard dampers and top mounts.


This kit allows ride-height reductions of up to 35mm compared to stock whilst providing excellent compliance on the road and increased body control during performance driving on both road and track.

The standard GR Yaris has been met with high praise the world over. Having covered many miles in our own development car, we agreed that the stock car was an exciting recipe. However we knew that we could improve upon the standard spring setup without spoiling the work that Toyota have done on their dampers.


Working with Eibach, we assessed the OEM setup and knew that we wanted to maintain the road manners and compliance felt on the standard springs. In addition, we wanted to reduce weight transfer to help improve body control during performance driving on the road and track through lowering the car’s centre of gravity and some subtle increases to spring rate. Finally, we wanted to provide the ability to cornerweight the car for fine-tuning track handling.


Our adjustable height performance spring kit utilises dual-rate springs front and rear, manufactured by Eibach, to help maintain compliance when the wheel travels from rebound into bump.


After testing on both the road and track with GT3 driver Jonny Cocker from JCR-Developments we settled on spring rates which are increased by 15% front and 20% rear over standard. The increase in spring rates and slight additional rear bias work together to reduce weight transfer, improving direction change, turn-in response and rear axle support mid corner.

Our black anodized aluminium bespoke adjusters sit over the OEM dampers and allow up to 35mm of ride height reduction over standard, allowing the driver to tailor their car’s height to their own preference whilst opening up the possibility of corner-weighting for optimal balance on track. The adjusters use an allen-head pinch bolt to lock them in place.


We offer full fitting and setup of the spring kit, with ride-heights, cornerweights and geometry set to suit the customer’s requirements and usage. 

Examples of Yaris' with the spring kit fitted

Technical Specs Overview

Engineered and developed in-house at String Theory Garage, with Eibach & JCR-Developments.

  • Ride height change

    • Front: Up to -35mm​*

    • Rear: Up to -35mm*

  • Spring rate changes

    • Front: +15%​

    • Rear: +20%

  • Dual springs both front and rear, fitted with polyeurethane clip tubing to prevent coating wear

  • Springs manufactured by Eibach Germany to industry leading tolerances.

  • Anodized aluminium adjusters compatible with standard dampers and top-mounts


Available to purchase NOW

For any order placed before the end of June, we are offering the spring kit, fitment, ride-height and cornerweight adjustments and an alignment at String Theory Garage for £995 inc VAT - RRP £1195.

We ship worldwide - get in touch for a quote.




  • Kit only

£695 inc VAT

  • Kit

  • Fitting

  • Ride-height set

  • Cornerweighting

  • Alignment

at String Theory Garage

£995 inc VAT

Offer price for June only! 

RRP £1195