FMF Ram Valve
(Disclaimer: This is my opinion, with no technical data to back it up. I am not a mechanic, though I did spend most of my teen years working on cars at various service stations. Feel free to interpret that as you wish. I do most of my own mechanical work on my cars and bikes. I consider myself competent, but in no way an expert. I am not a racer. I ride for fun. I dont race because losing is not fun.)
Ill say it right up front, I dont like the FMF RAM Valve. I purchased it with an FMF Gold Pipe for use with my 1994 RMX250. I chose the RAM Valve because I felt it and the Gold Pipe would complement each other.
My first problem with the RAM Valve is the design. Installation requires cutting the stock rubber intake (piece?) in half and mating half of the rubber piece with a piece of rubber that FMF supplies. This hardly seems like a precision interface. By design, it left me with a lack of confidence. In addition to that, it leaves one in the unfortunate position of not being able to switch back to the stock configuration without purchasing a new part.
In stock form, the RMX is not a screamer. However I found its power delivery to be very user-friendly with reasonable amount of low-end torque, for a two-stroke. I tend to "tractor" up hills, and the RMX was good at this. After installing the RAM valve, all that changed. I tried a variety of jetting adjustments and was never happy with the results. The RAM valve did provide a small top-end boost, but the bike never had any real "power hit." On the whole I was very dissatisfied and recommend that you dont waste your time with this product.