2004 STi 106,xxx miles. i bought the car with 97,000 on the clock, and ever since i got the car the tranny will make a high pitch noise at 66 mph. 65 and 67 it isn't there Just at 66mph. I checked with Subaru and the 90,000 mile service was done. and the fluid level on the dipstick is in the correct spot. The only mod done to the the car is an K&N air filter. Also the spedo is 5mph off at any speed.. The tires needed replaced so I thought that was the problem, and it's not. I got stock size new tires on the car.. Any way to re calibrate the spedo?

 

Do you have the stock sized tires mounted on the car?

 

Yeah stock size tires on the car

 

Idk about your tranny noise but the 5 mph off on the speedo is common never seen a fix for it

 

5mph is ABS sensor/speed sensor.

Go get codes pulled at subie dealer and see which one it is. If no codes are shown, then the sensors are still within tolerances. Take all 4 ABS sensors off and the tranny speed sensor and clean the contacts.

Will fix the 5mph instrment cluster reader.
As for the noise, it can be a few things, are you sure it only occurs at 66mph? Maybe you're only conscious of it because you got used to it at that speed, try to pay attention if it increases as speed increases or it just shows up at a sudden speed.

 

The only code stored is the G sensor signal. The wheel speed sensors are all showing the same speed driving down the road, and the tranny noise is a noise, not just me hearing things.. My girlfriend and friend asked me what that sound was. No matter what road i'm on or what gear.

 

Fix the G Sensor, it's part of the ABS System on the STI due to the CAN bus. I also would recomond new ABS sensors even though they are within spec they are 6-7 years old and on an STI the braking system is highly abused.

As for noise, it can be the front tie rods if its in any gear- since that rules out clutch and gear wear.