My STi arrived at dealership. Salesman allows me to drive it to gas-up, car has not been prep yet. Taking it easy and shifting gears at 4K RPm's. 2nd, 3rd very smooth, 4th definite vibration at gearshift knob (RPM's went down to around 3K between shifts), shift to 5th and 6th and the vibration goes away??? Only does it at 4th! Does any one out there with his US STi 's felt this vibration? Do you know what causes it, will it go away or do I have a bad transmission in the car I will close in tomorrow, Memorial Day? Salesman felt it two, mechanics were not available (Sunday) to check. Need answer quick, thanks!