Mileage

[Chubosco]

I had an 05 H2 that got 14.7mpg and traded it in, now I have an 06 H2 that gets 11.7mpg. I bought both used so I really don't know why the difference.

But I am really thinking of getting crazy and spending 2 grand to put headers, catback, and modify the air intake.

That may seem crazy but I plan to keep this H2 for life. I don't drive it a lot. It is my baby.

Does anyone know how much the additions would increase mileage? I can see the increase in horsepower but mileage isn't clear at all.

Best guesses welcomed.