Would both of you please pay more attention!.. now I am bullying you..
I didn't think the pictures required any explanation but I've found another which shows a piece of box in the middle. The first pictures clearly have a "star" shaped piece here made of 4 bits of pipe section. So it's still working as a cruciform but with less restriction.
As it happens the images come from another forum and were posted by our own Nasher.
Gilps from here too, commented that the mod did not work on his and other's 600 and 620 DD racers and did not recommend the mod.
However on yet another thread someone tried this on an SS1000 and claimed better low down and mid range power at the expense of top end. (Hence why they didn't like it on the racers I imagine?)
I am mildly tempted to try this on a spare exhaust, and maybe even try and position the "star" to bias the rear exhaust to the left a bit.
Many other comments claimed that the original cruciform is not restrictive at all and is carefully designed for the best performance.
I would kind of go with that to some extent as, if you are going to bifurcate a pipe, then each bifurcation needs to be half the area of the main pipe to retain the same flow. this is what appears to be happening in the standard cruciform, so a big part of me is saying if it ain't broke...