hi guys,need to buy a brush for cleaning my 3 inch pellet stove outside 5 ft pipe.was just gonna buy a 3 inch brush but my friend said buy a 4 inch so it cleans better.he says there made of nylon and flex easily so a bigger brush would press against pipe walls and remove crud better.so do i want a 3 inch or 4 inch?was looking at a rutland or meeco,any recommendations?