So, Everyone's getting on the PhatBox bandwagon now. This is a good thing. There are a few of us who got boxes directly from PhatNoise and have had them in our cars for awhile. So, I'll offer these tips and pics to those interested.(I know the new ones have a somewhat different shape case, but I'm sure the dimensions are similar.)
As a preface, I've got a 2001 S4 Sedan (So these pics may not exactly match up - I understand there are some differences with the my2000 and Avants.)
With that being said let get into it...
As you can see here it does fit with the little door closed:
Take the cover off, and the toolbox out. (The toolbox latches don't scrape on the top of the PhatBox)
I've removed the PB - lifting up on it on both sides - the top of the PB hitting the metal shelf above to separate the two sides of the velcro - and slid it forward. Here you can see the cable from the CD changer connector (wrapped in foam in the background) to the PB - even this long cable tucks behind quite nicely. You can see here the self adhesive velcro on the bottom edges of the PB - the velcro on the right in this pic is narrower to match the narrower ledge on the left - not necessary, but a nice touch.
Another view of the bottom side of the PB, the CD changer slot,and the connector cable.
I used velcro like this but in 2 inch width which I trimmed down. (I got it at a hardware store, but WalMart or HomeDepot should have the stuff by the foot.
Here's the right side velcro. (I put the hook side on the car and the loop side on the PB.) I "dry-fit" the PB in the changer slot and drew lines with a pencil on the shelf and the bottom of the PB, to align the velcro with. I used 2 inch wide velcro and trimmed it. as appropriate. (Don't use your good scissors as the stickum is pretty tough stuff - for the same reason, be VERY CAREFUL to get the velcro in the place you want it - it ain't comin' back off easily.)
Here's the right side lip with the velcro cut to fit.
Once you've got the 4 pieces of velcro stuck, just attach the cable, tuck the extra length behind the slot, and holding the PB against the top of the slot as well as the left edge - keeping it away from the mating velcro, slide it back, until the front is flush with the edge of the slot, and then press down to mate the velcro. AND THERE YOU HAVE IT! Much easier to do than trying to screw it in and easier to remove if you ever need to as well.
Now for some bonus pics:
I have the First Gen (Actually Beta) Hardware and the back of it has an aux power connector, RCA plugs, and a serial port. (You do know this thing is running linux right?)
And the pinouts for the PhatBox-CD changer cable