you will have much better acceleration with the 11/14 bell... the 14/17 is too tall for the stock motor to handle...Others on this forum are running the 14/17, but they are running BB .28's in theirs... I have the os18, and I run the 11/14 with great results... 45 to 50 mph is about all this truck can handle without being too difficult to drive... mostly due to the short wheelbase and narrow track...