Dry pipes rip!..... but for a ocean boat I would not recomend it! When bashing in the surf they are known to come apart, where the elbow fits to the chamber....
The B-pipe limited chamber would be my choice, the chamder lays nice in low in the hull, so that you have alot less likely chance of it coming seperated..... its the most reliable pipe out there for the B1. imo
The Mod chamber will free up some more RPM's, but for surf you dont need it... only if you wanted to build a race ski..... and here again you may end up having issues, and possibly even crack a cylinder, as it wraps up over the motor.