this is just the reverse effect of when everyone was installing their units in spring and suddenly getting 2 more mpg.... when in reality they were just switching from winter fuels to summer fuels -shrug-

 

It wasn't until I installed the RB CAI that I experienced the drop in mileage; about 2mpg. I already had the REVi which improved mileage and performance. I was not expected a loss by adding the CAI. A few days ago I finally got my dealer to replace the plugs and check out my car for performance issues. The car is now running very nicely. I just filled up so I'm on my first tank after the tune-up. It SEEMS a bit better but I want to measure to make sure. I have 37,500 on the car and they replaced the plugs and updated the ECU.

I think after installing the CAI that the engine was now getting much more air than it had previously and it leaned out the engine, which made it much less forgiving of the condition of the original plugs. It's performing smoothly and strongly now so hopefully the mileage will go back to pre-CAI levels.

 

In my case, that's not true. I noticed the (slightly) better gas mileage when I was already long using the summer fuel.

 

is that really true^^^^

 

Update - Perhaps my Economy is coming back to before?

Just recorded 17mpg

 

Maybe you're just slowing down

 

Maybe I'm crazy, but:

1) Ishu has a point about the sound change. I swear that when I first installed it, that a redline run would rattle my interior (read: very loud). Now, however, it's just a nice throaty roar (read: Sporty, but pleasant) without being able to rattle anything anymore. I have no idea why...

2) I noticed ZERO change in my MPG. I get the average of 17.5 city and 21.5 hwy in the winter. The temperature definately effects my MPG. In the summer I get 19.0 city... ~9% increase.