[streetstar]

You have the wrong cam if you are concerned one iota about gas mileage

If the PO had a tunnel ram in mind, he was only thinking about straight line performance at high rpm's -- its gonna pass a lot of un burned or poorly burned fuel through at lower rpm's (anything below 3500)

I'd pull it, install an "rv" type cam, then go with the 600 . A Lunati Voodoo cam is a much nicer general purpose bumpstick as well