Hi TitusI know this hose well on the 2.2, where it's also connected on the thermostat housing. It's there to bleed air out from the thermostat housing into the expansaion tank. I'm not sure how your new manifold is constructed, but it sounds like a good idea to copy the setup from the guy with the pink filter. I would keep the hose thin (I think it's a 6 mm originally until it's stepped up, right?) because it was so originally - I don't think it would matter going up in size and making it a straight section, but I'm not sure either. Besides, you have the correct reducer already./Anders
By the way... I now have a Rancho. OH NO!!!!