Technically the 20R is not at all more powerful than the 22R. The 22R makes more horsepower and torque. Although I have heard many people give a seat of the pants estimate that the 20R is more torquey. This probably has to with the 20R hitting peak torque around 2400 RPM as opposed to 3400 RPM on the 22R (according to Wikipedia). That said, if you would like to retain the torquey feel of the engine, stay with smaller tubing. Opening it up too far just may switch your torque curve to high RPM, which isn't ideal for crawling. Although, I will say that I have either 2" or 2.25" (I will check later) tubing and some $40 muffler on my 20R and it gets around pretty good.
mines 1 1/2" pipe probobly stock,and a stock muffler with so many holes its stupid
