TOPIC:

My Zephyr has this extra thing on the exhaust, and I can’t think of any other bike that has it. I don’t even know what to call it. 



This photo is from the underside obviously, but it’s that protrusion right in the middle. You can’t miss it, I’m sure you know what I’m talking about. But what is it? Is it necessary? Some emissions thing? Can I cut it off? What would happen if I did? I totally get that this could be a bad idea, but if it’s not gonna hurt the engine performance, I kinda wanna try it. 

Looks like a resonating chamber, probably intended for the sound/back pressure of the pipe? ...then how to seal it if you cut it off? Can't unring that bell...
edit: looks like this could also be the stop for the full stand on your bike? What's that dent in the middle?

The KZ's had an equalizer pipe between the 2 stock pipes.

IMO, if you're still stock, you'll probably want to keep this... but wait for other replies.
 

It looks like a "resonator" removing it will change the tone of the exhaust (you may need to play with your jetting as well)

By !Seymore:  The KZ's had an equalizer pipe between the 2 stock pipes.

The Zephyr exhaust has connector pipes on the headers between 2-3 and 1-4.
I have no idea if cutting off the resonator is a good idea or not. leaning towards not. ha ha.

It's just there for looks. Those silly mechanical engineers what were they thinking.

Hahaha! Yep, purely aesthetic. 

In response to the comment about it functioning as a stop for the center stand, the bike has never had one, only a side stand. 

And yes, I would suppose that cutting it off would also require welding a patch on over the hole. 

On a 2 stroke, it's called an expansion chamber.....  

It's a resonance chamber.
Basically an empty void that absorbs / dampens  exhaust pressure waves to reduce noise at particular frequencies rather than fitting a bigger silencer..