I think they are electric. The back of the gauge only has 2 wires, and no vacuum nipple. I think it's specific only to S15's too. You can use the holder in S14's though, but you have to cut the top bit of the plastic to fit.
I am looking for a piggyback ecu for my 4g93 NA... there two is between my budget but i want to know the diff between this two.... E manage blue and Unichip Q ah..... which will be better for my setup up... CAn say...