Actually with an older 2.0 turbo I had (1990 Sunbird) I did notice when I had the muffler come off due to a bad weld done and I LOST 2-3 mpg over the 3 weeks and 4 tanks of gas I ran through it.

I would love to see the datasheets and engineering data on one of these engines. I have a friend who is in the know at Spring Hill (and told me of some impressive things done with the 2.4) so I will see if I can get something from them, including what is the optimal exhaust restriction.

 

On older cars yes. You were having the issue of lack of back pressure when the waste gate is open. Probably an internal waste gate at that.

 

josh, if your still following the posts, i tried to do a sound clip lastnight for ya, it just didnt come out rite dam cell phone video,i cant really tell you the price of the mufflers because i did a hail damage car for the guy at the muffler shop and he did the car . the header came from colbalt addiction.and its a magna flow cat back with two magna flow street mufflers. hope this helps

 

I appreciate it man I've got the magnaflow catback ordered, and if I like the sound I'll add another muffler and a y-pipe.

 

awesome let me know why you get it all done

 

Keep us posted Josh, I think you'll like the Magnflow system, have one on my 2006 and I like it. Just a tad more raspy than the GMPP/Borla systems on the other two, but it does sound good.

 

I will and I'm going to make a damn sound clip, because there isn't one anywhere for a N/A HHR. Lol

 

Someone always has to go first, you have now been elected Josh.

 

My MPG in the Edge: http://www.youtube.com/watch?v=Qy-T87QiM40