I got the Stage 1 upgrade a few hours ago. The drive home had too much traffic to let me test it thoroughly. My initial reaction was that the initial response is MUCH better. No more "light turns green, press accelerator...wait...wait...slowly move...now go".
I had a K&N filter in my Corrado. I LOVED the sound it made when you punched the gas pedal. If it sounds much better with the stage 2, I'm in! Debating getting the intake or the Eibach springs next.
Oh what fun!