For those who have the tank in their trunk and the pump under the hood...how did you run the line from the tank to the pump? Did you run the line under the car or through the cabin?

How does the STi water spray run the line?

I'm not sure how the STi runs the line. I have both the tank and the pump in the trunk (ran out of room under the hood). I have run the lines (1 water line + control wires) under the rear seat, from the rear seat to the center console (under the carpet), then up the center console through the driver's side firewall grommet.

I'm not completely done with the routing of the hose, but that's my plan at least.

I have a tank mounted on the passenger side of the trunk. the water line runs right behind the back seat, and under the edge of the carpet/door sill along the drivers side.

I guess that's how I will do it. Sigh.

I have the tank in the drivers side trunk, with a line running to the pump mounted under the car in the space above the muffler. Then I ran the line through the fuel line grommet spare hole under the back seat and down the driver side door sill and through the grommet under the clutch pedal coming out under the brake booster. PITA to route, but I could find no clean way to run under the car all the way.

I don't know if there is an elegant way to run the water line under the car (there may very well be, but I've never checked for exhaust clearances, etc.), but there is a tempting grommet near (may be in) the spare wheel well that will give you access to the undercarriage if memory serves.