gp performance - induction tuning for your motorcycle for Honda
Ram air - Fitted standard on most modern superbikes ram-air uses the bike's speed to pressurise the air box forcing more air into the cylinders at high speed. After market ram air boxes can be fitted to fuel-injected as well as bikes with carbs, such as the R1, but re-jetting and carb adjustments will be required.
Cost e.g. R1 kit £500.00
Hyperchargers - Although not strictly ram air boxes, they can give good results on cruisers due to a much less restrictive and free-flowing design. When used with a good pipe, e.g. Vance and Hines, they can give considerable torque and hp gains.
Cost around £180 plus fitting.
Air Filtration - Ram air bikes ingest a considerable amount of muck due to their forward facing air intakes, (can Suzuki's SRAD really stand for Suzuki Rain And Dirt?), a high flow serviceable filter such as a K&N or DNA can be a sound investment. Alarmingly, many filters on ram air Kawasakis seem to stay clean, as they can lift at high speed and allow dirt straight into the engine! Kawasaki owners check in you airbox, a K&N could save your motor.