I added one on a little 258 with a 70 on it. The boat never had any problem planning, but I wanted to be able to cruise slower looking for spots with the front not pointing at the clouds. The 258 is a short boat - less than 16 foot so the front likes to point up. I used a StingRay so I did have to drill into my plate on my motor. However, I think it is worth doing the modification even if it is a bit destructive. Now that I am making the entire behind the seat area a single livewell, I am hoping the hydrofoil will help counter the additional weight of the added water. I don't think you can go wrong using one. If the motor is under warranty, it may violate warranty using one. Food for thought.
Phil