the ninja uses a lot of extra power -however your robin engine is one of the few that has the hp to use one . you will not get a clean cut however and would be better off using a gator blade and side shooting . a reg snapper blade will work ok for side discharge too. honestly you would be better off using another mower for cutting thick heavy grass as the snapper tends to clog VERY easily. the gator blade is the only blade that does all 3 jobs on a snapper with any degree of satisfaction. it mulches great -side shoots great and bags well too.