I called GN1 and confirmed that the core support tab has to be cut and the bracket on the condenser has to be removed. He told me that the small 1/4 holes in the oil cooler isn't going to restrict the flow any. I told him BS, why did GM use 3/8 holes if 1/4 would have been sufficient? He then said that I didn't need the oil cooler, I said BS on this too, why did GM use a oil cooler if it wasn't needed? I have run my car with and without the oil cooler. Without the cooler, the oil gets black really fast, after it heats up, I have less oil pressure than I did with the oil cooler. In the cooler climates, one probably could get away without the cooler however it gets really hot here and is needed. I don't know if I could return it being as I've already drilled the oil cooler holes.