Yeah the LS1 panel box (panel type designs) are considered up there with high flow attributes. Seriously gave the LS1 some serious thought, but not keen on shifting battery tray (min 20mm) and have a number of elec pwr feed rotary switches that also need moving. Just too much.
I have also heard there is 30mm min clearance rule eg: need to have 30mm min clearance between any of the filter effective surface and the container inside faces (box or cyl) that it is housed in.
Also looking at these also $340 w/o fiter. Uses 150mm long pod K&N. Looking at options.