i recently bought a 2000 corolla lovelife. it was setup with a free flow muffler. i had it checked and got the carb cleaned. but i'm still consuming only 6-7 kms per liter. is the free flow muffler a big factor in the fuel consumption? one friend of mine said that i need to have it tuned again because of the muffler, would that be necessary? i hope you guys can help me... thanks