Hey everyone... I bought a custom mouth piece and will never dive without one again! I feel much more comfortable and in control. That being said make sure your buddy knows your equipment!!! This is because custom mouthpieces may prevent your buddy from breathing off your primary (which regardless as to what you think of as an octo, they might go for when they are in need of air). Especially if your buddy is significantly smaller, and the mouthpiece will not fit them, it could become dangerous if they are not familiar with your equipment. Hope that makes sense and sorry it is poorly written...
In conclusion, get a custom mouthpiece, you won't regret it, just make sure you have a reliable octo and your buddy knows where it is!