Well, what's the difference between Spark Arrestors and Silencers. I was looking through some magazine and saw ads for FMF, Pro Circuit, etc pipes. and was wondering what's the difference besides the Spark Arrestors being more $$$

A silencer is just anonther name for a muffler. The spark arrestor is an insert that fits inside the silencer. It is designed to prevent burning embers of the echaust from exiting the silencer. Arrestors are required in most Nat. Forests and many other areas,. Race pipes/silencers which are used on closed course tracks normally do not have arrestors as standard equipment.

couldn't of said it better