Understand the stock chute, but the stock chute that Estes provides is a bit underwhelming. The shroud line attachment is clearly not up to the load that a rocket of this size puts on it. The 18" canopy probably provides a safe decent rate, but the 9", 12" 18" & 24" plastic parachutes all have the same strength of line attachment - which is the polyethylene's resistance to tear out. Since they all have 6 lines, they all have the same max capacity of shroud line weight/tension. All that means that the 9" and the 24" chute wind up both having the same weight limit for the shroud line mounting, even though 24" canopy itself can support a lot more weight. The attachment point is the weak link. So, a nylon parachute (which will have the lines sewn on) is an excellent upgrade.