As the premier Monaro/GTO suspension parts vendor in the world, Pedders Suspension is proud to offer the widest range of springs to suit your specific application. The industry standard for variance in spring height is 15mm/5/8". Pedders Springs are manufactured to the highest standard in fact our own tolerance is 2mm or less than 1/8". Each spring undergoes a full scrag and is load height tested to insure long life and consistency.
The GTO has an average ride height of 600mm as measured from the bottom of the rim (OE 17" Wheel) up through the wheel center and to the fender lip all around. The standard variation would be a low of 590mm to a high of 605mm. This 10mm (5/16") variance is measured with a quarter tank of fuel. Your results will vary based on your baseline measurement.
Please note: Pedders considers the spring rate to be proprietary and confidential information. The rate at full compression is only an approximation to be used as a general guideline.