First of all, I bought this APST-1 Twang Banger with the thought of replacing a Mustang bridge pickup. If you know your Mustang's, you know they can have really low and dull output pickups to begin with.
So I wanted a more "beefy" clean tone and a great "dirty" overdrive tone, and the Twang Banger is a perfect match for that.
The downside is, because this pickup has a copper-plated steel bottom plate which the mounting screws mounts to and the way a Mustang is wired, in one position it will be quite when you touch the mounting screws, but in the other position when you touch the screws it will boost the ground noise instead.
There is a fix for this though, find the drawing of how the Kurt Cobain Mustang is wired and use that, it was pretty simple. You only need to wire the bridge pickup like the KC Mustang, once I did that, the noise was gone. The downside is though that the bridge pickup switch can only turn the pickup on, when both pickups are on only the neck pickup switch can swap the in/out of phase.
And yes, it adds even more Twang to your Mustang.