[rc4man]

The one you've sent the link isn't bad looking, especially if it fits your budget. Too bad about the cat thing, I can see why it's an "ex-roomate". Good looking scenery in the background, probably some decent riding roads in the area.
Exhaust systems are all about personal taste and part of making the bike your own. They're also something that can easily be changed later if not satisfied.
As for asking opinions, you'll get as many as for questions like which oil to use, what tires to run, and on and on infinitum. Do what you like.

 

[rc4man]

As an after comment, I had Two Brothers on a Suzuki 1000 V-Strom, Prior to that I had Yoshimura on a Suzuki 1000 SV, same engine, the SV sounded awesome, the TB not as much, even with the add on db reducers.
Yoshimura doesn't list a slip-on or complete system for the Vulcan S but they do for the 650 Versys and Ninja. I don't know how much difference there is in the models as related to the exhaust

 

[rc4man]

Here Ambam, maybe save you some money

Delkevic Full Ceramic Black Exhaust for 2015/2020...

Delkevic Full Ceramic Black Exhaust for 2015/2020 Kawasaki Vulcan S EN650 No tuning or remapping of the bike is required. There is no deceleration popping either. Awesome Deep Throaty Sound Easy Installation, Direct Bolt on, no Modifications needed Regular Price CDN $857.00 Sell Price CDN...

www.vulcanforums.com

 

[rc4man]

Or

Vulcan S 650 - Delkevic Exhaust & Engine Bars For Sale

Hello, I ordered two mods for my 2020 Kawasaki Vulcan S ABS but totaled the bike before the parts came. I am now selling the two unopened mods. Although my motorcycle was the 2020, they fit any year of the Vulcan S (possibly including the 2021). Pictured below are the two boxes in my garage...

www.vulcanforums.com