Originally Posted by smellme

Of course you should upgrade the whole direction, I meant don't take the short part into account. It's the long part that matters and there are only upsides to upgrading Sin-IST, so it's really a no brainer.

And FYI there is a difference in miles, but it's very small, something like 2000 between SIN-IST or SIN-IST-BUD/PRG/VIE.

Both IST-KUL and SIN-IST are on A330, but the KUL one often is without wifi.