Hi TJ,
While the 1:1 Bladerunner was a fast boat, getting the model running well is a bit of a struggle.
Call yourself lucky the stock drivetrain didn't come with the boat, it wasn't very good, the steering outdrive is a disaster (on any boat for that matter).
When you search the internet for builds (and rebuilds) of this boat you'll find that it's a bit on the small and heavy side to perform well.
Usually a 700 motor on 12-14 cells NiMH was the preferred way to run this boat reasonably quick.
With the lighter Lipo and brushless motors, I wouldn't muck about with twin drives (unless it you want it to be a floating and moving scale model), but keep it as light as possible.
Sharpen the trailing edges and strengthen the running surfaces where required, to stop the flexing.
Use a stinger with a seperate offset rudder.
To me this is the only way to get this stunning model running (really) fast.
Regards, Jan.