Sifu and Sifu's..... My Dahon Speed D8 is now more than a year. looking at upgrade and need help here in term of cost.

Current original using SRAM x7, 8 speed.

Which would be a better enjoyment ride. Based on original, mainly use gear 7-8, not much usage on 1-6 so need more 9,10,11......

1. To change double chainring in front to have 16 gears.
a) front chainring set
b) new front shifter
c) apa lagi....

2. To change cassette from 8 to 11 (ultegra 6800)
a) chain
b) rear shifter
c) apa lagi....

lastly boil down to cost also, which of the above set up would be cheaper or same same.

Thanks.