My global time manipulation mechanic is a hack, and just reduces the game's frame rate. By doing it this way, it was extremely simple, and produces *all* the side effects that I want... a general slowing of everything that the game does. It's a terrible solution, but I'm still running a proof-of-concept. If the game is fun, I can do this in a better way.

After that, there were a few simple SFX to implement... cannon fire, grenade fire... 
These were also simple. My audio wizard Lara Barden put together some SFX for me.

Next, for the engine noise I needed something special. And Stupidly complicated. It took me more than 3 hours to get it working right. This was dumb, and for a POC that will have like 4 players, it was a waste of time... but I learned a lot. 

The sound of a VW engine is special and unique, since my POC vehicle is a rocket powered bug, I needed to capture the unique sound of an idling air-cooled bug engine. I ended up ripping the sound from a youtube video, and breaking it up into different loops using audacity. I have one loop with an uneven pace, and one loop with an even pace. Then, I set the two sounds to play in order, a random number of times each. It worked out perfectly, and I created an idle engine sound that doesn't sound like a single looping track!

Next, I have a rocket engine. So I created a rocket engine loop (youtube+audacity again) that plays when the player is applying thrust to their craft. This did *not* work.

After a few hours of troubleshooting, I had to turn to reddit for help.