tune tune tune.
:P OFT is def an option as they have some good base maps to run, and there are a number of local tuners that can tweak them to match your mods as you go. But it should also only be a matter of time before the open source guys get everything finished up for ecuflash etc. There are lots of cheaper alternatives to ecutek coming for more basic stuff. Ecutek has more "feature" out of the box but i hate their system personally. But if you can afford it a custom tune with one of the experienced tuners out there goes a LONG way.
I am wanting to start experimenting my self and seeing if i can re-write some stuff to get flex fuel running but its a bit iffy experimenting on my car with how much boost i am running.