Originally, I tried installing a Walbro unit in my 11 STI, making the necessary modification to the fuel filter assembly to make the pump fit properly. Unfortunately, after installing in the car, it wouldn't hold pressure like it's supposed to. Must have botched the modification, but it fit perfectly and snugly so who knows. The DW300C however was a direct drop-in replacement, bought a new filter assembly to rule that out as a possible problem, and the thing slid right in and locked in place, no fuss, no muss. Car started right up after priming and has been performing beautifully.
I should have gone this route in the first place.
