What frequencies are the C5 Bose 8" woofers covering.

[DSTJ99]

Does anyone know some specs on the door speakers. Are they subwoofers or woofers? Could they handle a low pass filter, say 100mhz? I installed a cd player and seemed to have lost some low frequncy bass, and have too much midbass now. I was thinking about adding an inline low pass filter, but could only find 100mhz. I was thinking 250-300 would be ideal. It was a cheap fix i was looking for to hold me over for a while. I currently have the 8" woofer, 3.5" mid, and a tweeter wired in parrallel with the mid. plus the stock 6.5 in back. Setup sounds great just problems mentioned above. I think the solution might have to be to add a subwoofer in the trunk and keep the bass low on the headunit, just crank up the sub.