Andrew
Did a little Google search and I guess the R1 is so down on torque they don't need TRE's (Timing Retard Eliminators). You should be able with the help of an add on ECM device alter (advance timing at lower rpm's) and use what is known as an accelerater pump program to help your problem.
Honest Dad himself
PS>>>> the next time you flush the comode could you post back in which direction the water turns (clockwise or counter clockwise). I got a bet ridding on it.
