Want to achieve more responsive throttle city driving economy for MY12.5 VE Series II SV6 Z series SIDI, is there another option apart from tune?

Another option to consider would be our manifold spacers, as shown in the links below:

6.35MM MANIFOLD INSULATOR TO SUIT VE COMMODORE LFX/LF1/LFW SIDI V6 http://www.maceengineering.com.au/epages/shop.sf/en_AU/?ObjectPath=/Shops/mace/Products/MI627

12MM MANIFOLD INSULATOR TO SUIT VE COMMODORE LFX/LF1/LFW SIDI V6 http://www.maceengineering.com.au/epages/shop.sf/en_AU/?ObjectPath=/Shops/mace/Products/MI628 

25MM MANIFOLD INSULATOR TO SUIT VE COMMODORE LFX/LF1/LFW SIDI V6 (requires rear cowl to be trimmed)

http://www.maceengineering.com.au/epages/shop.sf/en_AU/?ObjectPath=/Shops/mace/Products/MI629