Today I installed a sway bar removed from a Jeep Cherokee, on my P15.  The Jeep sway bar had a much larger diameter (26 MM or 1.024") than the original P15 bar.  Took a bit of fabrication to put it all together, but the old gal has much refined road manners now.  Took a ride around the neighborhood, about 5 or 6 miles, and it seemed to work well.  I think I'll take it out on the highway tomorrow and see how that goes!  I'll try to post some pics if anyone is interested.   Wayne