do you hear a difference between (b) and (c)?

Don't know yet... the car is still a work in progress. It is pretty much complete except for the custom subwoofer box to hold the two 10" Xtant subs. That box is being built using the large trim panel (that extends from the rear door and over the wheel arch back to the tailgate) as a base. I give up a 4" wide strip of my rear cargo floor between the back of the wheel arch and the tailgate to the subwoofers -- the only compromise to vehicle utility that I made. (Well, actually... if I get in an accident that triggers the fuel pump shutoff relay, I will have to remove the sub box (4 screws) to reset the relay, and I'll have to remove the sub box if I want to replace the rear shock absorbers.)

I figure it will take me literally months to tune and tweak the system to my satisfaction. As you saw in the diagram I emailed you, there is an enormous amount of tunability in it.

Here's a hint for anybody interested in seriously tuning a car stereo: you can't rush it. All you can do is listen for a few days, and finally decide that, "Yes, there is too much sub-bass and the treble really is too bright..." Then you make a small change, and then listen for a few days more. If you try to tune it for an hour at a time, at the end of the hour you will be able to convince yourself that anything you do sounds great. Then the next morning you turn it on, and it sounds terrible. YMMV, but I have found that after 20 minutes, I can no longer make even a semblance of objectivity.

tanstaafl.

"There Ain't No Such Thing As A Free Lunch"