After installing my Megan Racing Drift Spec catback Exhaust system and driving around for a month I've noticed my mileage has decreased or perhaps stayed the same but the engine is running rich, whatever the case my gas gauge is more active. I can physically see the pointer drop in short trips and its driving me crazy.

After searching a few threads here the general report is that the mpg is supposed to stay the same with this mod. After searching Google, however, I read that having less restriction and less back pressure will cause the engine to run rich. So my questions are

Does the Megan Racing Drift Spec catback significantly decrease MPG?

What can be done to bring mileage back to normal retaining the MRDS system?

I've tried a few things without much success
1. Adding the silencer to create more back pressure
2. Keeping tire pressure at 32
3. Adjusting driving for fuel economy

No luck yet

I should also mention I have a TRD cold air intake.

The car has 63,000 miles on it and I haven't done any maintenance besides the minimal oil changes and tire rotations. I'm guessing the big 60k maintenance marker might improve MPG but would lack of maintenance cause such a drop in MPG? Will spark plugs and cleaning the MAF perhaps remedy the situation? Or is the only way of returning to stock MPG with stock parts?

I'll provide numbers as I reset my odo and gas up this week.

Thanks in advance!!

 

exhaust system such as megan should not affect gas milage,unless you just love the exhaust note and wanna hear it sing to you lol..i have the same exhaust,and i didnt see a difference,but you mention your car is running rich,meaning its dumping alot of fuel..the exhaust wont cause that unless you have a bad leak some where...

running rich is why your gas milage is decreasing...

adding the silencer will not help,ill just cause power lose and make your motor work even harder...

tire pressure will some what affect milage..and yes its the way you drive also that affects it

 

I have a full Megan exhaust system, headers to axel back, and I dont see any difference in mileage myself.

But when I installed mine, I unhooked my battery to reset the ecu. Maybe that would make a difference?

 

Check your PCV valve. After I installed my header and catback I was running richer and had more carbon build up from the unfiltered stuff. Lost a few MPG from that, installed a $4 PCV valve and now I get my average MPG again!

 

i added a airaid throttle body spacer to mine and my mileage went back normal

 

I cleaned my air filter and replaced my PCV valve and the mileage went back to normal. I hadn't cleane the air filter in two years. Thanks guys.

 

Lmao. Well there's your problem. Glad you got it fixed though.