steiale

Hack saves, I believe, are when the truck gets saved by turning the rear steer and front steer in opposite directions (I.E front wheels turn right, and rear wheels turn left). I’ve seen this most used in the context of when a truck is on its side and you hack save to pull it back over onto all 4 wheels. I could be wrong based off of what common law is amongst the league organizers but this is my interpretation.

First and foremost, extract your V4 folder. If it's a folder, the game can pick out that flare file (and many others) for every truck. \
Second, it has to be a track with a truck shop spawner to have multiple trucks at the same time.
Third, V4 trucks take up less memory than some of the trucks now a days with more details, so that's why you can spawn multiple V4 trucks.
Fourth, Sounds aren't that important IMO, so that's why I don't have an answer for you on your sounds question because I've gotten used to having no motor sounds on my trucks.
Hope this helps you out somewhat. 

Probobly something in here:
https://docs.google.com/document/d/1wV7l_jRVQfeNAdXY58dJQYkSq_wvaWeriwHY-e_cby0/edit#heading=h.5t2getgeng26