PiP rear spring rates

I've scoured the forum looking for the rear spring rates of the PiP and the standard Prius. I could swear I saw them in a post awhile ago but I just haven't been able to find it.

So, does anyone have this info? It's so I can get a proper rear spring rate for a set of coilovers for my PiP. Some say it doesn't make any difference and that coilovers for the standard Prius will work fine in the PiP's rear end, but I seem to remember that others felt it would make a difference, so I thought I'd get the info just in case.

Thanks!

Chris