Hey Jav, here are some tips to get a great race quality for a race.
-Do not use fixed host. This will deteriorate the race quality and if the host loses connection, then everyone is kicked and no race results will come out of it.
-Fixed host means that you are the host throughout the session. If you (the host) quit, or unexpectedly lose connection, then that means that everyone else will quit involuntarily. It is used to ensure a stable connection at the loss of race quality (a big and noticeable drop). This is also refered to as a star topology (basically), where one PS3 acts as a server and the other PS3s that connect act as clients.
-By having a non-fixed host lobby, you may run the extra risk of disconnecting, but is very seldom I've noticed. This is also known as a mesh topology (basically), were all the PS3s connected to each other exchange info to each other. I have yet to see a room host transfer over until the host quits.
-Set race quality to at least 4 stars. Voice quality doesn't matter.
Other than those tips, anything else is good.
I hope this helps you guys. Good run today and good luck later!