bars will do much improvements than rims alone.

care to tell whats the stock tyre size and width?

nanti recommend 255/45/ZR19 sagat pulak.

sounds like you want to be fast and at the same time want to save fuel.

BTW, changing tires or rims wont reduce the body roll. If you want the body roll to be cancelled out completely, adjustable suspension is your only way.

I'll pass on the tyre suggestion but normally a tyre which saves fuel wont be good in handling and vice versa.