We typically suggest Inconel exhaust valves over steel nitrided exhaust valves when you are forced induction / nitrous, where high exhaust temperatures are expected. Inconel valves are heat resistent keeping temps out of your head and in the exhaust where they should be. Turbo cars making over 800+WHP should always run inconel exhaust valves.
 
Supertech uses over 20 years of manufacturing experience to design and produce their Valves. Intensive testing and working closely with engine builders provides continuous improvements and provides the market with the best possible product for every application. High flow rate, durability and quality are all of great concern.

Supertech Inconel Extreme Flow Performance Valves for Pro Street and Racing are engineered for High RPM and High HP. Extreme Flow Valves outperform any other valve on the market today, and with their Nitride Coating are perfect for High Temperatures (and run cooler which improves value life), Nitrous, Turbos and Superchargers. For naturally aspirated motors these valves will give you a much greater cylinder flow for good HP gains.

These exhaust valves are one piece forged, high temperature, high nickel, stainless steel alloy. Valves are CNC finished to strict tolerances making these valves the choice for the most demanding race classes. These Nickel based alloy materials are used for exhaust valves in engines that reach very high temperatures and its use is growing with the application of turbos and superchargers. All valves are swirl polished, have stem undercut and a hardened tip.