DIY Dual Shower Head Kit for Easy, No-Renovation Upgrade

The user explicitly seeks a 'plug-and-play' solution to add a second shower head without 'tearing into walls or doing full plumbing reroutes'. They are looking for successful 'splitters, diverters, or extension kits' and 'pressure-balancing hacks'. This indicates a strong demand for a DIY-friendly product that offers the luxury of a dual shower without the complexity or cost of professional plumbing. A product could be a comprehensive kit including a high-flow splitter/diverter, a secondary shower arm/mount that adheres without drilling (e.g., strong suction, adhesive, or tension rod), and potentially a water pressure optimization feature or guide to maintain good flow with two heads.