I would like to add that while it varies no matter where you sit, however I noticed that during the last refurb when I still had AP (which was two years ago) that it seemed to increased the "wetness" you would get while on the ride. As it seemed as if regardless of no matter where I would sit, I would get wet on top, but nothing too drastic (in the past), however noticed after that refurb that I would get a little bit more soaked on top than I did previously and it was pretty consistent with me regardless of where I would sit. It seemed that JP got a little bit of a punch after that.
That being said, all I can say is, sit in the middle of the row? But yeah, in terms of water rides, JP is tame compared to rides like Rip Saw and PopEye.