Description DEF Racing 2020-2022 Yamaha YZ450F high-performance 1.5mm oversize stainless steel exhaust valves. Works great for all engine setups but works exceptionally well with larger bores and strokes. Motocross, Flat Track, Ice Racing and Drag Racing will all benefit  with these valve improving mid to top end power. The valve pair includes two steel exhaust valves, designed for increased exhaust scavenging, improved and durability. Product Features: Exhaust Valves: Increased diameter of 32mm (1.5mm larger) Must recut valve seat profile to fit the larger valve (OEM seat will accomodate this) Valve Stem Size: Remain OEM of 5.5mm Material: Made in the USA with high-quality steel for exceptional strength and longevity. Design: Proprietary tulip shapes and margin shapes specifically designed to improve airflow across all RPMs as well as increase piston to valve clearance! Piston to Valve Clearance: Designed to increase clearance for performance tuning and enhanced operation. Durability: Built to withstand the harshest conditions of drag racing and flat track competition. For the best results, we recommend using this valve set with a properly ported head to fully unlock its potential. Related