Having played with many Home Made Exhausts, There is something to be said for standard,
Good secure fittings etc, Also the 2 into 1 can help with sucking the ex' out, A good all round performance
can be had by just adding a straight pipe ending at the rear wheel spindle.
And as you say lightness.
I love best a pair of 2" open pipes, But I found bad ground clearance for road racing, They say power was only at the top end, but I did not find that.
For performance nothing came close to my home made, 2 x 1.5/8 pipes going into a home made collector box
ending at the rear wheel spindle with a HUGE open pipe,
My Brother in Law worked out the size of 2 x 1.5/8", Is was HUGE and what a sound, But I used it on the road
And went on holiday to the I.O.M. a few times.