Lingenfelter L650140709 Lingenfelter Cadillac CTS-V Air Intake Duct v1.3 - Manual (Page 7)

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13. We are now going to modify the factory
airbox. Any kind of cut-off tool or die grinder will
work for this portion of the install.
14. Using a flathead screwdriver or small pry
bar, pry away the air inlet from the bottom of the
factory air cleaner housing.
15. Use the next 5 pictures as a reference.
Use a silver marker and mark out the locations
on the airbox to cut. This is the front of the
factory airbox.
16. (Left side of factory airbox)
6.