If you are talking about the Tower Kaos ARF I expect you would be pretty nose heavy with the 4S. I had to add a lot of lead in the tail of mine and I only have an Irvine 53 on it and it is an ounce or more lighter than a OS 46. The 53 does pull it along smartly though. If you could find a Kaos kit you could move the firewall back to get it to balance.