So, here are my thoughts...
It's possible to achieve "up front bass" illusion with a well integrated mid and sub.
It's not possibly to achieve "up front bass IMPACT" without a decent sized, high output midbass driver in the front of the car.
I think there is a disconnect between these two results and most people are looking for a high impact up front bass solution, while many preach on here the ability to cleverly trick the mind with T/A and phasing, eq, etc. all the while using smaller mids...
While I don't disagree, what happens when you get any sort of volume from the system that only provides the illusion of upfront bass. As volume increases, the "up front bass illusion" slowly drags itself closer and closer to the rear of the vehicle. Is it really possible to achieve dynamic up front bass while using 6.5 mids or lower powered or lower xmax drivers? Or is it just an illusion that will fade away as volume increases?
I would wager that it is not possible to really achieve the impact without more cone area in the front.
Watching BowDown's thread and putting a sub up in his dash has got me thinking a bit more about how to achieve the "impact" that so many of us want. I have also recently finished my install, and have high output 8" midwoofers pulling midbass duty while three 10 wgti subs anchor the low down. The impact is seamless, and ALL up front. No matter how loud I turn it up, the stage and impact stays up front.
I'm not sure putting a sub in the front is the most efficient way of getting bass up front. While I am hoping to generate some thoughtful comments from those who are in the know, I think the take away for this is that you can't simply have the impact in the front that you want without increasing the effective cone area in the front of the car.