Matthew--- cutting it shorter will not alter the look of the density... it will however adversely -affect the ` look` of the system by cutting out the wave/curl of the hair..... you can thin it by using hair-removal cream in this manner, but go ` easy` ...do it gradually over a few days, as not all the hair sheds out immediately--some is weakened and will shed out over the next day or two...
http://www.youtube.com/watch?v=rPULkcyVD2Y and obviously you won`t be able to use it on the poly but a thinning scissors could help if used on the hair on that area....again, go ` easy`. It`s a new system and needs time to settle-down / in---they all look quite ` full` initially---act in haste and repent at leisure !!!