I ran a few RTA tests with the deep waveguides in the center baffle. e650's and e110's only. No e430's.
I captured the following driver and passenger side positions:
seat headrest (left and right ear sweeps)
dash center (aligned with edge of speaker grill)
dash middle
dash pillar
The dash center vs dash pillar shows a drop around 12Khz on up at the pillar.
The seat position isn't too bad compared to the previous kick panel tweeter locations.
seatvspillar by
Ryan Erickson, on Flickr
seatvscenter by
Ryan Erickson, on Flickr
centervspillar by
Ryan Erickson, on Flickr