Why its fuel consumption got higher than the usual,

Why my RR sport 2006 fuel consumption is 28L/100km, more than the usual that used to be 21L/100km, its power is not that powerful. It's original exhaust has been removed since I bought it on 2017.

crwdns2934089:0crwdne2934089:0 crwdns2934093:0crwdne2934093:0

crwdns2934109:0crwdne2934109:0

crwdns2889612:0crwdne2889612:0 0
crwdns2934285:0crwdne2934285:0