A puny 2 to 2.25" catted H. I think LMIIs don't sound too bad on a factory H. Pretty sure the stock size was 2.25, but don't quote me on that one. If you want to be sure, go rent a chain cutter from Autozone, and chop the tailpipes off, as close to the muffler as possible. When you do that, look and see if you are cutting a part of the muffler's expanded part, or the smaller pipe that slips into the muffler. I always cut as close to the muffler as possible, giving me the most pipe to work with with the new mufflers. It's easy to remove too much. A tad harder to add pipe. That, and if you cut close enough to the muffler, the size should be the same outer diameter on the end of the H and the tailpipe. Just take the tailpipes up to the store with you, and slip fit them into a couple different size pipes down the exhaust aisle, to see what you need. Good luck!