I'm not sure how this is even possible but, I recently changed my exhaust to a true dual with flowmasters 40 series w/o resonators and stock cat. I have been getting 16 to 17 mpgs intown. When I installed the FI HFC, an X-pipe, and some resonators on (because of to much rasp) I have been getting 22 MPG INTOWN!! that is amazing I think.

I understand that the stock cat are restrictive, but is it really by that much?

Secondly, the resonators that I have put on are baffled rather than straight through. Does anyone know how restrictive these are?

The guy said they are from magnaflow, but I could not find anything that resembled the same design. But now my exhaust is extremely quiet, but with no rasp, which I wanted. I now think that the exhaust sound almost like a stock g37 sedan. At first I didn't really like the sound because it seemed to quiet, but if i get that much improvement in MPG I would definetly live with it.


Sound Clip Link
http://www.youtube.com/watch?v=B_X8APkDzSI

 

Flowmaster 40 series on a G?? I had those mufflers on my f150.

 

I know I know, if I had chance to change the exhaust I would, but I got them because they were cheap and I hated the stock exhaust rattle.

I know we get what we paid for and I always loved the sound of flowmasters on my other cars (domestic V8s) but yeh a recommondation from me, DO NOT GET FLOWMASTERS on a high reving V6, to much rasp at the highend, but great rumble on the low.

But has anyone experienced this much gain on MPG by changing the exhaust setup?

 

Did you have any changes in driving style after the exhaust changes? A couple mpg's is common but what you've seen is pretty extarodinary.

 

Actually my driving style has not changed. Since I have been modding the exhaust I have been listening to the tones at all levels. I have a regular route that I take to test this. I usually floor it on the straights, check midrange power on the curves, and various other test, but my driving style actually has been pretty "spirited".

When checking my MPG I try to keep all variables the same, except for the weather, but the weather has been consistant since I have been gauging the performance within the same month.

I hope that my performance wasn't effected by the (what I think) a restrictive baffled resonator.

Any idea on the resonator that I have put on? never seen one like it but it looks pretty restrictive but it did the job of toning down the exhaust note.

 

Curious to how this sounds... Any sound clips?

 

Doesn't sound that great, but I'll post some sound clips Sunday because I have to go out of town this weekend.

 

i think flowmaster officially wins the award of being on every known vehicle to man kind

 

My MPG went up in my '04 Maxima when I put in some Cattman headers (with already installed catback and y-pipe)... +4MPG on average, and I actually push the car a bit more now... since it's more fun and all...