Originally Posted by IOevo

im pretty sure i know what it is.

your new "invidia" DP, does it have a flex joint? if not, then whats happening( PROBABLY) is that all the stress from the motors major moving parts (crank shaft, connecting rods) are slowing down considerably fast, and causing the motor to shake. ever played with a gyroscope? when the inner wheel is spinning fast, the gyroscope has little vibrations and moves smoothly. when it slows down the balance gets all off kilter and the g-scope falls over. So, when engines are turned off, the motors momentum causes it to shake, because of the rapis reduction of movement. with the stock DP there is a flex joint in it, that lets the vibrations from the motor kind of "absorb" into the flex joint and your car doesnt shake.

having a flex joint in any DP i believe is mandatory because without it, you will be putting high ammounts of stress on the connecting points where the turbo connects to the exhaust manifold, the engine head, and anywhere else that connects to the motor. ever seen an exhaust muffler shake when someone revs the motor? do you want that shake to travel all the way up to the exhaust manifold and head connection, possibly putting high stress on those bolts? not me...