If you're looking at the ones with the builtin tweet(I think you are) they are internally crossed and will most likely present a 4-ohm load to the amp. That's how they are with the MB Quart RSC 216 pkg in them.
To be doubly sure, you might just give Boss a call or email...
atrick@hydrocide.com">patrick@hydrocide.com
or
800.405.WAKE (9253)
I've found their customer service to be very helpful