On mine the upper part fit fine but the metal box that holds the cruise control module interfered with the filter a little so I took the Dremel to it and removed the part of the box that was in the way.
As far as replacing the plastic splash panel, I would. Some guys don't but some guys have lost their filters when they came loose. I don't think there would be any performance advantage to leaving it off anyway.

 

Theres another pic of part of it...all ive got of mine

 

Thats what I thought, because the filter and the tube isnt that tight of a fit, perhaps if you drilled into it and used a nut and bolt combo..thats an idea.

 

Anyone got pics of the LPE from under the car? I hear its a tight fit.

Also do you think the LPE is functionally designed better than the SLP? (with that huge filter)

-Dustin-