[Classic]

As I recall the larger hose goes to the air intake for fresh air so I'm not sure there's much point in blocking it off though it would do no harm to do so. Your exhaust popping could also come from an exhaust leak at the heads. Did you use new exhaust gaskets when you changed the pipes? Did you re-use the chrome acorn nuts for the new V&H exhaust flanges? If you did, they have probably bottomed out without snugging up the header pipe to the exhaust port because the V&H flanges are thinner than the stock flanges. DO NOT tighten the acorn nuts. Take one off, go to the local hardware store in their metric fastener section and get four new stainless steel flange nuts, not acorn nuts, then go to the nearest HD dealership and get two of their exhaust gaskets. The HD gaskets work perfectly and seal better. The flange nuts can't bottom out so you can get a good seal with proper torque, about 15 ft. lbs +/- and I bet this takes care of the popping. Make sure to torque the flange nuts evenly a little at a time and after riding the bike a few times, re-check the torque. You can find the HD gasket part number by using the search function of this forum or over on the Delphi Vulcan forum.