I had the same this happen to me. I went with the TRD and exhaust and my mileage went from 27-30 to 24-27. Not bad though. I did notice that I have to shift at 3-3500 RPMS to get a little better mileage than when I used to shift at 25-3000 RPMS. i don't feel bad though because when I did the switch I got rid of the delay when you hit the accelerator and take off in first gear.

 

The trd exhaust did not do any of what you just said. An axleback is not increasing your hp output, causing the car to consume more fuel, and especially is not providing you more throttle response.

 

I didnt say anything about hp output an I ment to put down intake and exhaust. It was just too early and I put down TRD instead lol.

 

CAI create more power when there is COLD AIR. CAI dont create cold air. unless you throw a couple ice cubes in there you engine is getting what ever temp the air is outside your car.

 

You are incorrect.

The ambient temp of the air decreasing has the same effect with or without a cai. Of course a cai pulls in cder air when it is cold out... So does the stock intake!

A COLD air intake (hence the name) pulls air from outside the engine compartment and as far forward and low to the ground as is practical. The entire purpose of this is to avoid air around and above the engine, which is warmer. Cooler air is more dense, so you can burn more fuel at a given volume for a given afr. This is how they increase power. That is the entire reason they are called a CAI.

Now, there is a component of reduced resistance on airflow, but that is also a small effect comparable to our intake design and lots of new ones these days.

One reason a lot of cai's do worse than you expect is heatsoak. A metal tube heat soaks like a **** at low speeds or sitting still. This actually has a detrimental effect on iat that negates the positive effects. The plastic the stock intake is made of is actually better for this, and is why the "gfi" solution is a good one.