BOURNE HPP K-SERIES VALVE SPRING SET BOOSTEDThis Bourne HPP valve spring set is designed for Boosted builds and will handle between 350 700bhp (boosted). The spring set is designed for standard fitment using original platform shims and retainer setups. The valve spring diameter is the same as original Honda Type r valve springs so you can upgrade the valve springs without changing the spring bases or retainers. A fantastic upgrade used to run most aftermarket camshafts with max lift 14mm or