I noticed that so what I did is simple, but can't be seen.
I had some standard pipes left over from a build and I modified them and stuck them underneath the side overhang above the tracks facing backwards and used the mesh panels to allow the fumes to escape.
the actual exhaust is hidden behind the side skirts, but they are there.
I do enjoy these "What If " kits as they give you some freedom to invent a timeline and camo patterns etc. It is a licence to do some messing about in a theatre of war and timeline using kits done from original and concept drawings of the time.
The Lowe was a series of drawings done as part of the competition for what became the Tiger II. There was the original concept drawing which is AH Lowe kit and another version which is AH's VK 7201 kit. Both these were done by Adler and had originally the 88 /L71 gun fitted. Hitler asked for a bigger gun so the 105mm with the perforated muzzle brake was specified with an option for a 128mm for the rear mounted VK variant. Along with the drawings was a submission for redesigned shorter breeches and recoil system for the 88, 105 and 128mm guns.
There also might have been a STUG variant with a 128mm /L68 fitted that was on the Lowe chassis, but looked very much like a Jagdpanther. In the archive records I have seen in Germany, this concept was discussed in a few letters and recorded in minutes from meetings, but I have not come across any concept drawings or sketches. Those might not have survived or even been done.
It does make for a fascinating area to work in and kudos to AH and Trumpeter to give us that opportunity!