Has anyone installed a catback sys and modified the air intake on an H3 07?

I would be interested in hearing the increased mpg and any noticeable increase in power.

 

Yep. MagnaFlow CAT Back will get you some nice sound tone with coll dual tips, and help get the most out of the next two performance mods.



A PCMforless tune set to take advantage of a performance intake and the CAT Back makes a very significant difference. I consistently get 18.5 MPG combined, and can do a bit better in the summer when temps mellow out again.



I am not a fan of the open intake designs and prefer an enclosed filter to keep mud, snow, and water off the air filter element. I run and recommend a K&N air filter with all our intakes.

 

One can't help but wonder why, if it's that simple, GM doesn't offer that as an option, or even as standard equipment and up their CAFE. What about the payback?

 

Why does gas milage go down when its cold? Cold air into the engine should be making more horsepower...

 

When I say cold, I mean cold, like highs in the low 20s. All your lube fluids, T case, Trans, Diffs, crank, are like a milkshake. Even when up an running, sure the driveline heats them up to the low end of the operating range, but they are not as slippery as when it is 70 F, hence mileage drops. Additionally, in the great north, they add etoh for the mandated winter blend to battle gas line freeze up, and the efficiency of the burn goes down. Winter = MPG drops.

Extensive intake testing data shows that intake temperature at the extreme cold scale does not produce power. I can tell you all the Olds OAI ram cars I have ever tuned make the most power at an intake temp of 50-53 F. Of course those are carbureted without computer controlled tuning, but it does illustrate my point.

I can tell you driving 200 miles at 75 mph when the temp never busts 6F, will get you some crappy mileage.

 

Mike, I agree, but that makes entirely too much common sense.

Mass produced autos shoot for a happy (really crappy in my book)median, trying to make the grocery getter as quiet and reliable as possible, and also making them idiot proof enough for the average consumer to drop the kids at soccer, run to the store, and pick up the dog at the Vet etc... without fear or anoyance.

A performance intake makes a bit of roar when you mat the throttle. Gear heads and auto enthusiasts dig it, soccer moms and tree huggers freak. They do not want to be frightened[]when they pull out of the Mall onto the main road to head home. Hence, factory exhausts muffle the bejeezuz out of the noise, and rob power, intakes have resonators and accordian rubber/plastic hoses that muffle the intake charge, and rob power, and the power control modules are tuned to expect air drawn in thru a pinched straw, burned at mid throttle positions, and blown out a cramped and defusing exhaust system, and therefore are not set for the best possible power or MPG. Performance, and MPG suffer, but the average shmuck, .... the buyer the car companies are aiming for, is none the wiser and thinks all is good.

That is why these forums are a home for the modding enthusiast types.

Oh yes, GM does offer the GM Performance Air Intake (06/07 H3 I5s)... for about $400.00+ you get a foam filter, a shiny chrome looking tube and air box lid (with GM performance logo stamped in... WOW!) and rubber PVC hose, andworm gearclamped rubber coupler. I have many observations I could share about this version of an intake, but I will save that for another day.

 

Doc, will just replacing the stock air filter with a K&N do anything for mpg? Or do you pretty much have to go the intake, filter, cat back route to notice any real improvement?