I purchased a Sprint Booster for a 2015 Impreza (not wrx). This car is really underpowered and there was a very annyoing and noticible delay in the throttle response and it really did make a big difference. I traded in the Impreza for a 2013 Edge. I don't really notice a delay in throttle response on the Edge. I'll probably get a programmer, but I don't think I'll be getting the sprint booster for the Edge.