They usually are. It's been donkey's years since I went to see the bangers. There was one with a ramp and the winner was whoever did most sideways turns in the air. What amused me was the pasting all these MOT failures took before enough bits fell of to stop them. A friend's brother used to drive in them and his prep was mostly to just put in a scaffolding roll cage, replace the rad with an oil drum in the boot and sledge hammer all the wheelarches up so they couldn't shred the tyres. The old Sweeney style Granadas were very successful. Probably more safety rules now - I've seen a wheel come off and go through the crowd.