Where can I see the difference on a 3.5 chassis vs AA3?

[speedmachine]

As per title, where can I see a difference in my tubes (3.5) vs a regular 3, surely there is an extra tube or different routing of tubes to achieve 15% more stiffnes

[phil4]

The most obvious one is at the back just behind the drivers seat. The 3.5 goes /|\ whereas the 3 only has |\ there's no third one.

So here's one of my old 3.5, you can see the 3 we're talking about on the right side of the pic:

IMG_2485.jpg (2.01 MiB) Viewed 244 times

Whereas on this pic of the recent Atom 3 for sale, you can see it's missing the rearward one (I've drawn it in yellow).

3.png (921.15 KiB) Viewed 243 times