So I've decided that I'll be wanting a short little muffler on my exhaust, and since I'm planning on upgrading to a lunchbox air filter and a rejet, id like something less restrictive or more "upgrade-friendly." Here's the look I want, has anybody found a brand or model that worked well for them?

That looks like the stock can that has been shortened

I'm not looking to copy his set up, I just like the shorter muffler look.
I can't stand the sound my bike makes right now, something needs to be done

So cut yours and make it shorter. Done.

eBay up a 2nd hand Yoshi with maybe a damaged end... Chop it... Seal it.. Weld it on...

Mate did it with his 600 gix ... Worked fine... Could hear the howl coming 3 mins b4 he got there ... Sometimes... 

Delkavic shorty muffler fits your criteria.
http://www.ebay.com.au/itm/190758346623 Find one with a downpipe that fits or use yours.