There's nothing wrong with using holes(perfs) on the tube, IMHO making louvers is a waste of time and if you push them into the tube they will only add restriction and maybe some flow noise. Sound doesn't need to be "scooped" with louvers. FWIW when automotive OEMS use louvers they push them out of the tube, not into it.
The vast majority of aftermarket systems use perfs. OEMs use perfs. The only time I'd consider using louvers is if I wasn't going to put any sort of packing around the tube (perfs can whistle if there's nothing backing them). You can use stainless steel wool to knock down the whistle but it won't cut the high frequencies as well as fiberglass would. Then again, with the small size of the outer pipe even fiberglass isn't going to do much there.
Speaking of small size, a 1.5" OD tube inside of a 1.75" OD tube means a gap of less than 1/8", that's hardly enough to do anything more than a smaller tube would do with no holes. There's a reason mufflers are big, you need volume to make a difference unless you add restiction.
All that said, the bike will be loud enough that flow noise and a slight whistle aren't likely going to be an issue, so basically... I'd just drill holes in the thing and run with it. I doubt it will whistle adn there are other ways to adress it if you don't want to use packing.
As for how to fix it and where to put it I'd put it at the outlet of the pipe and hold it in with a screw. That is if I was running drag pipes. Which I can't imagine I'd ever do.