I basically faced the same problem when I bought my bike. The PO had used aftermarket fuel lines, which are fine, and the right size, but were hard to get off due to the routing and area they are installed.
I did some research and ended up purchasing the stock lines. Even though they cost a bit more, they are pre-curved, and route ever so sweet out to the petcock.
The thing I really like is, now when I go to remove the tank, I remove the outlet hose from the petcock (a slight twist of the hose & it pops right off), 2 bolts that hold the petcock bracket to the frame, and the who thing lifts out with the tank. No gas spillage, quick & clean.
I'm sure the same could be done with aftermarket lines, depending upon the routing and petcock location. But with mine, since the aftermarket lines have a bigger OD and are less flexible, it wouldn't work given the space all the stuff had to move through, and I didn't really like the way it was so jammed pack in there.
