I bought this silencer for my 2007 CR 125 which I use for Hare Scrambles. It replaced the stock silencer which eventually started to sound beat up and "ratty", even with fresh packing.
Installation required a bit of shimmying to get things all in place, but it took no more than five minutes to install the silencer. The pipe seems to hold up very well to the abuse dealt by woods racing; soap, water and a sponge will restore the silencer to brand new condition. I haven't seen any dings or scratches from rocks, which I am sure have been hitting it.
The R-304 Shorty performs exactly as advertised, it increases power in the low end of the power band. The increase in power is very noticeable, and a big help for GNCC's and Hare Scrambles. If you race motocross, the regular R-304 would be a better choice for it's ability to increase power in the mid to top end.
Overall the R-304 Shorty silencer is an excellent choice for a two stroke silencer, it's lightweight, powerful, sounds great and is relatively inexpensive; and paired with the Pro Circuit Platinum pipe it works even better.