honda ridgeline

I just purchased an 06 Honda Ridgeline. I have to say I am impressed with this truck. It is fast and very very very smooth. I drive an equal amount of city and highway miles. I have gone threw 2 tanks of gas (around 20 gallons each time) and I am averaging 19.7 miles per gallon. I think this is very good considering I can pull my boat with no problem using this vehicle. I am considering putting an upgraded muffler system on this truck as I can gain more horsepower (around 7 horsepower as well as torque) and about 2 miles to the gallon. I have also been looking into a cold air intake as I have heard I can gain the same amount of horsepower and gas mileage. The muffler system is about $600.00 and the intake is around $250.00. Let me know if you have done anything like this and how it worked.