Yikes - a 3" Exhaust on a non turbo 4 cylinder will hurt MPG/Torque and Horsepower pretty badly. I wouldn't even put it on to test it.
I just bought Magnaflows high flow cat, a Dynomax Glasspack (both 2" in/out) and Couldnt be happier with HP increase/mpg and Sound. If your gonna go the route of new exhaust, id say to go 2" - 2.25" Max


2000 Audi TT 1.8Turbo Quattro
1988 Chevy Camaro - 100% Built + for sale!