I made it into hackaday.com and figure I might as well celebrate the project almost being complete.
Saw this and thought it was worth my first post! Really great idea I wish my motor was quick enough for me to be interested in how much G I was pulling :)
I was just thinking, could you pull some of the data directly from the car itself (i.e. from the ECU) via the OBD port which a Subaru must have, then you could measure air temp, fuel mix, knock, loads of things without any external sensors?
Just a thought love the project though.
I suppose you could start to tap into the ECU. Interfacing with OBDII doesn't look too hard. It does take up some program space though. I decided that this project would be independent of the ECU from the beginning. That way I can put it in whatever car I want and I don't have to worry about frying and expensive ECU.