Jumbo is tourist shit... fkn terrible food
see if changi village hawker centre has re-opened yet, if it has, just go there
if not, take the MRT to Dakota station and hit up the OLD AIRPORT RD hawker centre.
here you will find food 10000 times better than pepper crab and it's easily doable with 6 hours.
just look for the long queue's and go to those stands and just order whatever they are selling.
I had some of the best food there