Hey everyone new to the forum so not so sure if I'm posting this in the right place but here's my post. I bought a 2013 ninja 650 and loved it at first, like many we all get bored of the same old and want to upgrade. So I wanted to get the yoshimura exhaust. The price is a little steep at the moment for me and was looking for another option with out taking out a chunk from my walet. So I heard about drilling your stock exhaust to boost up the sound and that way you won't worry about custom fitment issues which I was going to do. So I tried it out and I have to say I'm pleased with the results, given the fact that the parallel twin engine dosnt sound as sexy as the zx6 or 10. It wasn't a bad sound a small popping but very minor, and I'm still able to retain the back pressure by not eliminating the muffler.
The tools I used were a

Drill
Hole Drill bit 1" 1/2
Drill bit 1/2"
12 mm with ratchet
Mig welder + them welding skills

And that was pretty much it.

I spent like $20 for a long drill bit

$20 vs $600 for a full system we all know what the DIY would pick.

Took me about 40 mins just don't rush through it make sure you get the work done right so you won't have to redo it.