I traded in my 06 H3 for a 2009 H3 Adventure. I love it but I am somewhat surprised by the change in mpg versus the 3.5l. I am averaging about 280 miles per tank (20 gallons) when compared with my 06 that averaged about 330 miles per tank. My 06 had a K&N fipk that I installed. I was not that impressed with the quality or fit. What intake would you recommend? K&N has the original fipk and the cold air intake. Are there really any differences? Any other intakes that are better? I will also be putting on some type of exhaust. I have read the other threads and it appears the verdict is still out on the Magnaflow. Some people appear to remove the resonator and install a flowmaster. Any perfermorance increase from either set up? I live in PA and have emmisions testing. Will removing the resonator violate the emmissions laws?

Also, does a 2009 H3 adventure with the 3.7 have the cast iron front diff or is it still the aluminum diff? At some point I will put on 35s. But with only 9k on the odometer, it is not time yet. I don't want to start grenading diffs.

 

Yep, All 09-10 Adventures should have the cast iron diff. Put the 35s on? But I thought you are worried about mileage?

As to the first part of your post. I don't know, I didn't buy my HUMMERs for mileage and I modifed them for performance on and off the road.

 

Advent. pack. has cast iron diffs.

But a K&N fipk?? Cold air intake? What the f*ck? Is this a honda civic? Yes there are better intakes. Get a f*cking airdoc closed box system hooked up to a safari gear snorkel. I get about 400-430 miles per tank highway on my 3700. Bone stock.

You aren't gonna be grenading any diffs by putting 35's on.

 

400-430 miles per tank????? 17-21 MPG?!! Dang. I wish I got that. I'm only getting 250 miles per tank. 280 is running on fumes. I put 35's on and leveled it the day i bought it so I never got to enjoy that kind of mileage... for 400 miles to the tank I might consider switching back to stock... Thats awesome.

 

What's a 3700? I guess somebody actually does use the old vortech # system?

The 3.7L I5 is an LLR

 

Yep 400-430miles per tank with a BONE stock pos air filter (dirty). After I do my airdoc intake and K&N filter I'm thinking I can def breach a few mpg over 20

Oh they dont use that number system anymore? I've not been a GM guy in years and really haven't started following them since I bought my HUMMER. But LLR got it; gonna keep that in mind hehe.