Correct you cant do the balance with the engine in the car, Mine was done at vibration free, where they actually run the crank and pistons etc in the block - there is a video on my website of this and it comes out with really good results. The flywheel I got was as I said, very close, but having said that it wasnt the flywheel from the actual engine that they copied & I have seen different cut outs on the back of them. To be sure its the same, you need to copy the flywheel thats in your car! As you dont want to do that, you could always sent the old and new flywheel to Vibration free- they can match your new flywheel to the old one, & balance the clutch as well if you really want.