wasted spark for the l6 is a £400 job on it's own.... then there's mapping.

something like omex, which i went for, has wasted spark, launch control, anti lag, closed loop etc all there to make use of and you can buy it and a semi assembled loom for sub £700 if you shop wisely. the only thing that lets the 600 down imo is it's lack of sequencial injection which the standard ecu does have so going to batch injection from sequencial is a slight step backwards but it doesn't out weigh the benefits for me.

as has already been said though, decide who is going to do the mapping and perhaps talk to them as they each seem to have a system they prefer.