You want to high pass the component set as low as you can.
A few things to note. The lower the crossover point, the less power handling the speakers will have. The higher the crossover point, the less midbass output you'll have. You need to find the happy medium.
It really comes down to, first, how you have your doors treated. If you have them deadened and sealed, you may be able to the 80-100 hz range. If you haven't done anything to the doors, then plan on about 120-150 hz. Either way, set your gains correctly then play with the crossover point till you find that happy medium I was talking about.
The passive crossover will not high pass your mid. It will only high pass the tweeter and low pass the mid at whatever crossover point it's designed for. It's probably somewhere in the 3500-4000 hz range.