If you drive your GT turbo everyday back and forth to work then why is it such a bad thing to use the lower grade fuel? Why are you a cheap skate? Are you really going to need full throttle performance in stop and go traffic? Keep your foot out of it and save even more. If you want to go out and thrash it then go fill up with hi-test (maybe find some 100+), do a few full throttle runs to adjust and have fun.
