My '09 Savage has 27" wide handlebars.  Wonder how much wider I could go without changing any cables or wiring.  I'd like to go 31" if it's an uncomplicated swap.  Thank you!

What bars did it come out with?
If you're just a little bit short, rerouting them can get you some slack.
When I did the fork seals I rerouted mine and found a few inches. Didn't need them for longer bars. It made hanging a fanny pack between the bars and windshield a lot easier and let me pack more in it.
It's nice being able to unload pockets and carry a grease pencil,toothpicks, change for a toll, gun for a troll, smokes,waddevah..

I'd start with a good light and eyeball the routing of the cables. It's Not even unlegal to take some weedeater line and run a piece on the existing cable routes, if you need to  leave it longer, so you can zip tie one end, mark it, then pull it out and try to find a route that works better. You might need to pull the tank. Don't lose the speedometer O-Ring.

If the valves aren't making noise the engine is going to get hurt. It's just the design. It's noisy.