I think in China they have decided that distributing electricity is easier than distributing oil. Much the same in a way to Finland who decided cell phone infrastructure was easier than land lines a lot earlier than others.
That's nice. It took me 10 mins to walk to the BTS. Only leaving 5 mins at 2mins per station, not including waiting for a train.
15 mins can only have been thought up by a committee who never went anywhere.
Friction loss. What a load of twaddle.
The friction loss for 2 x 45 is almost identical to one single 90 bend. (2x 2.5 vs. 1 x 5.5)
In the OP's case he did add bends but friction loss depends on velocity.
If the new intake works fine just leave it be.
In gutter down spouts the 45 vs. 90 discussion centres on blockage due to birds nest et al not friction loss.