Nosing around and came across a setup specifically designed for the X350 (not one of those generic universal kits) and am actually curious if it's worth its weight in day old fish sandwiches or makes a neat little mod with a small performance boost and adds a bit of a growl to an already snarling cat?

Never played with the cone setup, just K&N filters.

So...am I proving P.T. Barnum right if I pull the trigger?

 

K&N panel filter is fine, but NEVER fit an open (i.e. cone) filter under the hood, it will cost you power as the filter is sucking in hot air compared to the original box filter that gets cold air (and no a heat shield doesn't keep the hot air out), and last but not least it will lower the life expectancy of your supercharger (the hotter that gets the earlier the bearings will go).

 

Basically what Avos said. With this little addition. If you have a car with a mechanical throttle body, use caution when using an oiled filter upstream of any sensors. If you have a drive-by-wire car, not worth the risk. If you get oil film on one of those throttle bodies, oh boy! I have been a proponent on k&n and AEM for years but wouldn't use an oiled filter on my 05.