13101-HE0-505 PISTON COMP. A

You can buy one here http://www.partzilla.com/parts/detail/h ... 0-505.html for Price: $76.43 OR you can buy one off evilbay http://www.ebay.com/itm/HONDA-PILOT-FL4 ... 4897.l4275 with a Starting bid: US $120.00

don't forget the rings you might want to locate them BEFORE you buy a piston, is your wrist pin, bearing and clips good?

Last time I checked the pistons were no longer available from Honda. Hoser you are right though you would need to locate rings first.