Supertech Subaru STi 100mm Bore -20.5cc 8.3:1 CR Coated Pistons- Set of 4 (Excl Rings)

If you're rebuilding the engine in your Subaru STi and looking to handle more power or fine-tune your compression ratio, a set of high-performance forged pistons is a critical component. These Supertech pistons are specifically made for the STi's 100mm bore, featuring a -20.5cc dish that results in an 8.3:1 compression ratio. This lower compression is ideal for boosted applications where you need to safely run higher boost pressures without detonation.

Forged pistons are significantly stronger and more durable than cast pistons, making them a popular choice for performance builds and engines that see hard use. Supertech uses a robust forging process to create these pistons, ensuring they can withstand the increased cylinder pressures and temperatures associated with performance tuning. The 100mm bore size is a direct replacement for stock, but the -20.5cc dish is a notable change that lowers compression. This makes them a great option if you're planning on significant turbo upgrades or custom engine tuning. Remember that these pistons are sold as a set of four and do not include piston rings, which will need to be purchased separately.

When installing these pistons, it's important to follow the manufacturer's recommended clearances and lubrication procedures. Because these are a performance part designed for higher stress, proper assembly and break-in are crucial for longevity. Ensure you have the correct ring set for your application and consider consulting your engine builder or a trusted mechanic for specific installation advice tailored to your build.