hed trauma
New Member
- Joined
- Sep 1, 2010
- Messages
- 2
What the title says.
When i went to go do my U-Bend delete/3" DP, i decided that i didn't like how the stock pipes were looking. (some rust, resonator had a slight crack)
I decided to go straight pipe from the catback (2 3/4"), Besides making the idle (and everything else..) absolutely loud, i lost a few mpg (while cruising) in the process. I did gain a few ponies @ the top end.. from what i know the stock 1 pipe in/2pipe out muffler on the Regal GS is supposed to be really restrictive, not to mention the stock 2 1/4" pipe.
I threw on a cherrybomb where the resonator used to be to quiet down the exhaust a tick, and have less drone @ highway speeds, my gas mileage did not come back while cruising.
Before the straight pipes (and eventually glasspack), the car did around 35mpg @ 55, 31mpg @ 65, 27mpg @ 75 (pretty linear, i know)
Now i'm getting 27mpg @ 55, 24mpg @ 65, 22mpg @ 75.
It almost seems like OD isn't coming on because i can kick down to 3 on the gearshift, and my mpg doesn't go down but 2mpg @ any given speed, which assumes that the car is cruising in 4th w/o OD. Also, I used to get crazy high numbers (MPG on DIC would peg 99mpg and stay there) when going down a big hill, now it doesn't go much above mid 70's.
So what do you guys think? Did the loss of backpressure do something to kill my gas mileage? I have no check engine lights or SES, so i'm thinking my O2's are fine, besides the fact that the ZZP PCM deleted the rear O2/EGR codes. Cat looks great, looked it over well before doing the new exhaust.
When i went to go do my U-Bend delete/3" DP, i decided that i didn't like how the stock pipes were looking. (some rust, resonator had a slight crack)
I decided to go straight pipe from the catback (2 3/4"), Besides making the idle (and everything else..) absolutely loud, i lost a few mpg (while cruising) in the process. I did gain a few ponies @ the top end.. from what i know the stock 1 pipe in/2pipe out muffler on the Regal GS is supposed to be really restrictive, not to mention the stock 2 1/4" pipe.
I threw on a cherrybomb where the resonator used to be to quiet down the exhaust a tick, and have less drone @ highway speeds, my gas mileage did not come back while cruising.
Before the straight pipes (and eventually glasspack), the car did around 35mpg @ 55, 31mpg @ 65, 27mpg @ 75 (pretty linear, i know)
Now i'm getting 27mpg @ 55, 24mpg @ 65, 22mpg @ 75.
It almost seems like OD isn't coming on because i can kick down to 3 on the gearshift, and my mpg doesn't go down but 2mpg @ any given speed, which assumes that the car is cruising in 4th w/o OD. Also, I used to get crazy high numbers (MPG on DIC would peg 99mpg and stay there) when going down a big hill, now it doesn't go much above mid 70's.
So what do you guys think? Did the loss of backpressure do something to kill my gas mileage? I have no check engine lights or SES, so i'm thinking my O2's are fine, besides the fact that the ZZP PCM deleted the rear O2/EGR codes. Cat looks great, looked it over well before doing the new exhaust.
