Remap definately worth it, anything else depends really on whether you want to or not. Nothing else will make nearly as big an increase.
I have a SS exhaust which imo definately improved economy, though I don't have any hard proof on this as it was simply based on the drive to and from getting it done (although it was tied in with a day out and was a few hundred miles so not just a drive up the road).
Also have a K&N filter, and you can argue that it doesn't do much performance wise, but performance wise I think the standard air box is a bit of a joke... So you may aswell get an induction kit if you want to mess with that. The re-usable factor was on the cards for me, but after you've cleaned an air filter a few times you begin to wish you'd stuck with the paper filters.