Is it just to help silence the machine ... i dont think you need that huge snakeing hose they sell .... although length is more effective , i think its more for venting to the outsude of the building your working in .
You could make a fairly effective silencer with something simple like ... the exhaust hole is 4" or so ... get piece of 4" plastic drain pipe , two foot or so ... line it inside with a layer of foam ( piece of camping mat or whatever ) . Attach to the machine hole with a 90degree bend so it runs along the body and is not in your way .
All the vac silencers are just a bit of foamlined tube or box . Even a short one will do something to reduce noise .
https://www.youtube.com/watch?v=Jf7qyIvi_O0The vacs are cooling themselves by taking in air from the top .. so in the airflex they are upside down and the cooling air is drawn in from beneath the machine i think . I dont think the exhaust has a lot to do with cooling .
Machines like alltec have the foam silencer built in making them great for indoor work . Definitely need silencing if you want work in a hotel .