I run mine for the same reasons as stated above. I also use the stock one like sanddudes. The increase in noise levels is minimal imo, not even close to a aftermarket pipe. Just gives it a nice deep throaty sound(wasn't that a movie? LOL) But I am a firm believer in running one, I know it is the law in my neck of the woods to run one at all times and I have read of people having their's checked by the certain individuals when they have been stopped.....Irv
http://www.swfire.com/faulty_spark_arrestor.htm