Why does the tank have 2 vent lines and why do they run all the way down to the rear links? I doubt the tank is airtight, as I have had gas come out the cap when I've dropped it. Any thoughts on plugging the vents or cutting the lines shorter to get rid of the majority of the lines? Do the aftermarket tanks have these vent tubes or just the typical one on the cap?

 

as the gas goes down you have to be able to let air in..... yes you need them... you could shorten them.....