Distorque has released a free distortion plugin for Windows, based on the MXR Distortion +.
Here’s the structure of the whole effect:
Input attenuator -> Input HPF -> Pickup simulation LPF -> Op amp gain -> Op amp HPF -> Op amp bandwidth LPF -> Upsampler -> Op amp clipper -> Output HPF -> Output LPF -> Output attenuator -> Diode clipping emulation -> Downsampler -> Volume
Details and download are here.