The update may be financially important to Apple. Partly because current iPods are seen as redundant to iPhone buyers, iPod growth is expected to fall from 35 percent this year to 13 percent by 2009. By adding a touchscreen and Mac OS X to the already higher capacities of the full-size iPod, Apple may be able to persuade the public that a separate device is still necessary. Should the new iPods share parts in common with the iPhone, this may also improve Apple's margins, estimated by Piper at a conservative 30 percent instead of the 40 to 60 percent figures suggested by others. The group does note though that while Apple pays approximately $20 more to produce an 8GB iPhone (versus a 4GB model), it charges an extra $100. Furthermore, 95 percent of 253 iPhone buyers surveyed on launch day chose the 8GB product.