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.
Hi guys.... hav been read this forum and jus register it....
Im zree from Brunei and using Evo8, was happy to find out this forum so i can learn all bout evo,this is my 1st post.. so hope u guys accept me as a Evo...