In relation to the VE MACE SIDI OTR, is it essential that we get a tune? Will it be fine to postpone for a few months or would I be better off doing the entire package together?

Ideally it would be good to get a tune done at the same time. In saying this though no fault codes should come up with our OTR.Though if you're on a budget and have a manual VE V6, then it should not be a problem running the OTR in the short term.