Secteur Sport - Shimano 105 Upgrade

bushhpd
bushhpd Posts: 7
edited April 2010 in Road buying advice
I am looking to buy a Specialized Sectuer Sport (budget does note stretch to the Elite).

Is it possible to upgrade the shifters from Sora to 105 at a later date?

Would it require other parts to be replaced also? ...the Secteur Sport comes with:
9 speed rear ring
Tiagra rear derailleur
Sora front derailleur

Thanks!