Yea this is posted in Deville section but I know not everyone has a 4.9 and a deville so im posting here too.

PVC from homedepot and a K&N Cone element filter

It was a project getting the filter over the PVC at first but it ended up getting on after a couple tries.....

The PVC is painted in Engine coat which resists heat over 500 degrees and so far there is no bubbling so I know its doing its job.

Engine sounds great at full throttle and you can feel it accelerate a bit smoother.
http://i6.photobucket.com/albums/y241/mrmateo/Me___Mateo/cadillac007.jpg
http://i6.photobucket.com/albums/y241/mrmateo/Me___Mateo/cadillac006.jpg

Thanks for sharing the pictures. I'd be interested to find out if there's any reasonable way to channel more air to it from the grill or air dam.
As it is, it still looks like a pretty do-able, cheap mod.
Good job.