This is my favorite mod to my 620 EVER! It's a way I carried a part of my past riding heritage with me from my super bike days. I had a zx10r, it was the first, and so far last, new bike I ever bought. I got an uber expensive Kenny Roberts racing (KR Tuned) stainless and carbon fiber exhaust. When I gave up super bikes I fabbed one of the cans into a muffler for my 620 to carry some memories with me and give the bike a trick look.
Here's pics of the exhaust before on the zx10:
Ktm exhaust before:
Ktm exhaust after: