a3 springs on a1?

[foxxinabox at wideopenwest.com (Foxx (in a box))]

   i was looking into different spring information, more for towing 
capabilites than racing, and came across a reference that a3 springs 
could be substituted for a1 springs AND be stiffer due to the weight 
differences between the two. any idea if this is truly the case? thanx.

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