i have a 2006 LT2. only mods are csg air intake i travel to ca alot from vegas. before i had a flowmaster put on, i averaged 33 mpg on the hiway. with the new muffler idid have alot more hp. times when i would be in 4th, i could put it in 5th gear. coming home thru the el cajon pass, my little hhr was a 85 mph rocket. before, a few times i needed to down shift to 4th. everythings good except that i lost 4 mpg. 29 was the best i could get. a plus for the muffler is that it sounds very good.

 

I've got an IMCO 924 on my 1LT 2.2L HHR. On my recent trip to Kansas, I got anywhere from 29.8 to 34.5mpg. The 29.8 was when my boyfriend was driving (85mph) against the wind and the 34.5 was when I was driving 75mph against the wind.

 

Which Flowmaster model did you use? My local exhaust shop wants to put one on my HHR and I am curious what model you choose. My shop recomends a Stainless Steel model.

Joe_WaZoo

 

Aren't all Flowmasters stainless like Borla or Magnaflow?

 

i do believe all FM and MF mufflers are Stainless. BUT some MF use a fiberglass packing and some use a SS packing. It changes the sounds a VERY small amount.

The decrease in gas mileage could be a side effect of a heavier foot and downshifting your HHR would have helped with the MPG since even though you are in the higher RPM range you're not pressing the gas as much as you would with a lower rpm and climbing the same hill. Could have been fighting a headwind, could have been a warmer day. LOTS of possibilities. Don't blame the poor MPG on the muffler. 80% of the time its driver error! And 60% of the time it works all the time!

 

this last trip to ca was about my 10th or 12th in my HHR. i try to drive the same way each time, seeing i've been driving for over45 yrs. i've hit all kinds of weather on my ca trips. before the CSG it would get 30mpg, after 33. i'm going back next month and in sept. i should be able to get a good average then. the flowmaster on my HHR is a 40 series. color is a dull gray.

 

Just a regular 40 series or deltaflow?

 

Unless there have been a recent change, they still have the standard aluminum models also.

 

its a delta flow. i'm wondering if the scavenging effect of the muffler is right for the 2.4 motor. if you look at the flowmaster web site, the pic of the eg2006 mustang gt, has the color of my muffler.

 

Flowmaster 40 ser. black case. Sounds really deep and can set off car alarms in the parking lot. I love it.