It should not void your warranty, but *some* dealers will give you a hard time about it should you need any sort of warranty powertrain work done. I've personally experienced this with a previously owned charger. The work was done but I had to *****, moan, and complain to FCA directly for a week. The only thing that got me through was I had a professional contact in their engineering staff, and he intervened on my behalf.
Fortunately the HEMI is port injected, so running a catch can isn't really all that necessary (vs a direct injected motor where you'll have a ton of buildup since there's no gas to wash those deposits away).