So the cat on my 87' GT went bad and started rattling like crazy. I ordered a cheap walker cat on eBay for ~$57 for a simple easy fix...... Not really that easy. I cut out the old cat and in the process shortened where the cat mounts by about 1/2 inch total but now the exhaust pipe going from the cat to the muffler touches the oil pan. Should I be concerned? I've driven about 100 miles like this and haven't noticed anything.

You shouldn't need to worry about heat transfer, but I would worry about the movement of the exhaust pipe wearing a hole in the oil pan. Remember that the entire exhaust system vibrates quite significantly and it moves with the engine as it rocks back and forth under acceleration and deceleration.

quote Originally posted by Bloozberry: You shouldn't need to worry about heat transfer, but I would worry about the movement of the exhaust pipe wearing a hole in the oil pan. Remember that the entire exhaust system vibrates quite significantly and it moves with the engine as it rocks back and forth under acceleration and deceleration.

That would be my concern as well... And for a $3 coupler from autozone, why chance it...