i put dual mac catback exhaust on my 2000 v6 mustang, and k&N air filter, and noticed a drop gas mileage, and i know there isn't any leaks..don't know what happened????

 

Give it a tune up. Also I believe you should have a custom chip and redyno with every mod to get the max performance out of what you have. On newer cars, every little thing you do changes alot of other parameters. Not so much the K&N, but the exhaust does in my opinion.

 

Where would be a good place to get it dynoed at?

 

I'm in Cali, so I couldn't tell you. Ask around at the local Stang Clubs. [sm=smiley20.gif]