IMHO thats a little too high to cut. you're gonna lose alot of lower midrange, and they will probably sound "tinny". The freq. response of your speakers should be your starting point for considering where to cut, and pretty much any full range speaker will play well below 600hz You will probably be looking at a response of around 125hz with a 3 1/2"..... Your midrange frequencies start at 250hz, which is where I would recommend cutting them.
![Two Cents](http://www.the370z.com/images/smilies/twocents.gif)
By the way, Woofersect has a set of Hertz 3 1/2"s for $99 FYI