3dBlurToFWHM before or after bandpass?

Since 3dBlurToFWHM uses the temporal noise profile to estimate the smoothness - does it make a difference whether I use it before or after the bandpass? I tried to empirically determine this by measuring the smoothness before and after bandpass with 3dFWHMx, and it seems my bandpass increases the smoothness just a bit.

So I suppose it does.

Would you recommend I smooth before or after the bandpass?

pro-before: this seems more intuitive, I set the spatial data straight, before I start modifying timecourses

pro-after: this would allow me to more precisely specify my target smoothness (as the bandpass will slightly modify it). But I’m wondering if this “modified smoothness” is even meaningful any more

I would do it before bandpassing.

However, I’m currently doing work to replace 3dBlurToFWHM with something better, but don’t know when that will become available.