I have a V6 VT Holden having a stock ecotec engine, I was just wondering would I need to buy anything else if I bought "BORED OUT 69MM THROTTLE BODY"

Technically you don't, however, it would be recommended that you have a re-calibrated memcal to suit if you have an automatic transmission. We can supply a suitable memcal separately, as shown in the link below:

http://www.maceengineering.com.au/epages/shop.sf/en_AU/?ObjectPath=/Shops/mace/Products/MEM609/SubProducts/MEM609