I'm looking to replace the front iso rubber pucks. Have a urathane one and an aluminum one. I'll be fabbing a pair for my next race car project. Can I assume that the puck is just a filler? Can I fab a pair fron delrin or aluminum, depending on what is the lightest, and drill some additional holes to loose a few more ounces? I've already replaced the 5 mph impact systems and fabricating a much lighter front bumper. I'm very weight conscious.