What will you use the bow for?

If you just hunt the stock string will work just fine.You will want to replace it every couple of years to be safe.

If you target shoot you may want to consider a string made with high quality materials "IE: Winners Choice". During 3d Season I shoot my bow every weekend and twice a week. This is a lot of shooting for a stock string to handel. And I was unhappy with the stock string after 2 weeks. The string does not have to be a winners choice but it should be made of 8125 material and be prestreched.