To upgrade your MACH II to a 16 oz or 32 oz flyer, contact your local dealer.
You will need to order a Flyer in that size for the MACH (not an Upgrade, which includes the Head, Flyer, Bobbin, and Orifice bar - but JUST a Flyer which does not include the Head but includes all the other pieces you need to get spinning) - your dealer can order this part for you and have it shipped to your address.