This modification converts the 800r Rave valve to exhaust pressure activated like the 800HO. The advantages are numerous. The valves open earlier taking advantage of the motors power sooner. It eliminates the possibility of faulty Rave solenoids not operating the valves correctly. Dyno testing shows a more even power delivery and higher hp and torque at lower rpm in the midrange. For this modification we need your complete valves and housings. WE DO NOT NEED THE BARRELS! We will include new rave gaskets , and springs with the modification. This price is per each valve and requires you sending us your valves. We modify the rave housings, pin (drill & tap the rave valve halves and install stainless screws) and send them back to you. Price listed is for one valve modification. Send just the 2 piece rave valves and housings only in clean condition. IF WE HAVE TO CLEAN YOUR OILY MESS IT WILL BE EXTRA! We will return them ready to assemble with new gaskets.