1000 Motors- Since the exhaust valves don’t open until 6800 rpm, there is a loss of torque from 6300 to 6750 rpm in the mid-range. By installing our exhaust valve spacers your machine will see gains of 6-8 hp in the mid-range with the stock exhaust, and 8-10 hp if you have an aftermarket exhaust system. It adds a lot of mid-range power and broadens the powerband at an extremely low price. Machined out of aluminum, sold as a pair and comes with a easy install instruction sheet. 600/700 Motors- Designed for carbureted F6/F7 models. Since the exhaust valves open at such a high rpm on the carbureted models the mid-range power is sacrificed dramatically compared to the EFI models. A recent dyno session at Dynotech has proven that our spacers drastically improve mid-range power by 10-14 horsepower. It adds a lot of mid-range power at an extremely low price. They also work well on 800cc big bore kits to allow exhaust valve clearance from the piston without machining. Machined out of aluminum, sold as a pair and comes with an easy install instruction sheet.