The 27 x 12 x 3 (core size 20 x 12 x 3) will fit without notching the bumper supports and will handle a ton of HP. I actually used the 31 x12 x 4 unit on my first build and had to notch the bumper mounts. The eBay unit I picked up had two threaded bungs on the top and bottom. I just drilled two holes in the radiator support brace (once you take off the grill and bumper) and mounted it below. Then I ran a couple steel straps fron teh bottom two bumgs to keep it from swaying. Ran it like that for 20k miles without a problem.





With the Denali front bumper cover, you want have to cut anything and it looks really clean once you put the plastic grill back in place.

Rick