Originally Posted By: Best F100
If you are looking for a 21" powerful mower, look around ebay or craigslist for a used Lawn Boy 2 stroke. It is my understanding, that the 6 1/2 HP ones, were the most powerful 21" mowers produced. I have (two) 6 1/2 HP Duraforce versions which regularly cut grass over the wheel heights, without stalling.
With the 2 stroke mowers, you get the added bonus of being able to cut up any grade of incline without engine lubrication starvation.
Plus, these have excellent rear wheel drive that really puts the traction down.