Honda's CRF150F is a great trailbike that raises the bar for off-road motorcycles for small riders; the XR100R it replaced seems almost toylike in comparison. The CRF chassis is fully capable of handling all the performance the stock engine puts out, so naturally, the search is on for more. Some performance pipes make the 150 way too loud for the sort of campground riding for which the bike is designed. We installed an FMF Q quiet muffler with the stock headpipe so we would be stealthy enough for off-road riding parks in Southern California. The surprise was the performance increase.
The Q boosted the power throughout the rpm range without getting us booted out by the neighbors. The pipe is throatier than the near-silent stock pipe yet quieter than the stock pipe with the baffle removed. It also ran better than the unbaffled stock pipe. Some of the louder pipes with aftermarket headpipes we've sampled seem almost too open, as if they are too much pipe for the stock engine. The engine felt very happy with the Q on it. We installed slightly richer jetting, then went to play at the minicycle track. The bike worked even better. So far we haven't seen any Q muffler that wouldn't pass the California 96-decibel rule, so it is reasonable in terms of sound; in this case, the $289.99 Q was lighter and a bit more compact than stock, with excellent performance. Now we have a 150 that is more fun on the play track but isn't an ear-sore around the campground. That combination works for us.