Maruti Udyog today reported a 12.9% increase in total sales for the month of April at 43,127 units against 38,190 units in the corresponding month a year ago.The company's domestic sales for April were up 12.4% at 41,574 units against 36,972 units in April 2005. The exports grew 27.5% at 1,553 units during as against 1,218 units, a year ago.