Garage Exhaust extraction

Hi all, Has anyone created their own exhaust extractor type thing in their garage? Like what you see in the NCT.

I had been using long pipes of flue extractor pipe and run it up and out. The issue was that it just kept falling off the end of the exhaust no matter how far "up" the exhaust I put it. I assume I'd need something more of a clamp.

Background to this, I have classic minis, and sometimes I run the engine when doing a few bits to them. One of them is a full rally spec engine, so it's fairly loud. I don't want to leave it sitting on the driveway annoying my neighbours, so ideally, have it on the garage but without killing me with exhaust fumes!