As dry as it iss around hear you and we all are better off leaving the spark arrestor in. It is only a screen. the restriction it causes it not noticable.I do not notice a significant sound change on the Foreman w/ an HMF w/ or w/o a spark arrestor.
IMO the stock pipe w/o the spark arrestor and endcap souds terrible. its just plain annoying. You probably will since a little increase in power if it is rejetted, but it would not be worth it for me and the other around me to put up with the noise.