Vacuum gauge for me, I didn't feel like having an obtuse rectangle on my dash was cohesive to my interior, that and lean burn makes any calculations hard to ensure are correct
Anyways the vacuum gauge is great to see the engine load. Best mod by far, it's hooked into the main pcv line on the intake manifold
On the civic my best tanks are with no pulse and glide, just using a light foot and keeping the vacuum gauge in the green as much as possible. Lean burn or not my civic seems to be very effecient even at idle
