Sorry for the late response I have been out of commission for a long time.... Long story.... Anyway I just ran the IBS line under the floor of the dash where the drain/vent lines were already running then out of the wall in front of your feet and to the IBS. Yes it drains from the same johnson pump that it fills from and vents from the new thru hull beside the one for the center bag that is now also a vent. Note you need to use a one way valve on the vent if you want it to suck the bag flat.
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2008 MOBIUS LSV - Acme 1847, GIII w/1100lbs Vdrive, IBS, PPSG, Wake plate, Z-5, Kenwood 700U, Kenwood Kca-RC107MR , Exile SXT65, Kicker 700.5, Kicker 350.4, Polk MM651, JL 13.5 Thin-Line Sub.