Can anyone recommend a setup progressive or sonic, size? Im about 160lbs w/ gear and i ride 2up with my wife alot she's probly about them same. Ive already upgraded to the katana 600 rear shock. 

I would use progressives.They progressively get stiffer the more weight you apply.Sonics and Racetecs are streight rate springs and are best for a single rider.I have progressives, 15w oil, and Kat rear shock.Riding 2 up is not a problem and I'm 200#'s.

Thanks , which spring is recommended for this kind of riding? kg's

This should help http://pantablo500.tripod.com/id2.html it also list the part numbers.I had to call MAW.The springs were $60US shipped.