Hey bro, looks pretty good! Definitely saves a lot of space

If you want to get a perfect (or nearly perfect) match on it, you may want to consider carpeting it. The materials can be found dirt cheap at your local hardware store (Home Depot for example) and it would be VERY simple to carpet that panel (and it would look great)!
Couple of questions for you:
#1) What kind of power are you running to those subs, and at what volume do you usually play your music? I ask because you are going from a bandpass enclosure to an infinite baffle mount... If you like to crank up the bass and have a high power amplifier you may have some issues, however if you listen to your music at moderate levels and have an amplifier that pushes right around the RMS rating of the subs (or a bit less) you should be fine... Infinite mounts reduce power handling, so just be careful and you'll be alright (and don't crank it with your trunk open)!
#2) What kind of wood did you use (and what width)? From the shots it looks like you used 1/2" thick plywood, but I'm not sure... If so, you may want to step up to 3/4" (and consider using MDF fiberboard, although plywood will be fine and actually weighs about half as much). 1/2" will have a lot of flex (esp on plywood), and it may not support those subs properly (weight wise or pressure wise). If you did use 3/4", just ignore this question (it was hard to tell from the shots)!!
Keep in mind, It won't be nearly as loud as the bandpass, but it will have much better low frequency extention and transient response (ability to perform quick musicle changes), so it should sound pretty good!
So.. most important question:
How does it sound??
Enjoy it bro!
-James