I'm running a Evo7/8 ECU on my Galant. No SAS (yet), but the Evo ECUs have some neat tricks to increse spool-up. I have positive pressure from 1800rpm and >1bar at 3000rpm with my evo 3 16G.
response after shifting/cornering is absolutely no issue. If above 4000rpm there is nearly no lag at all, so i never felt like needing SAS hardware...
For mild anti-lag with some pops and bangs it's enough to keep the throttle slightly opened (adjusting the idle switch to its max position is sufficient), check at what load cells it will run when off-throttle and give it some fuel and negative ignition timing.
this will also give a nice single "pop" when shifting up /ubbthreads/images/graemlins/grin.gif
only drawbacks: idle will be @ ~2000-2500 rpm and every routine depending on idle condition won't work anymore