Worst case scenario, if 06 AWD aftermarket lowering coil springs/suspension kit is not manufactured I want to look at my options.

I went on Tein's website and analyzed the spec's for the 06 300/430 lowering springs (S Tech, High Tech, and Super Street Damper). I found out that there is a correlation to ride height and spring rate. The funny thing is the Tein part numbers for the 300/430 are different. However, the spring rate and lowering heights are the same. Reference:

GS430
http://www.tein.com/ti/l78-uzs190l.html

GS300
http://www.tein.com/ti/l78.html

Does anyone know if the O.D. of the coil springs are the same for the 300/430RWD and 300AWD? If so, I can't find a reason why after market coil springs for a GS430 from Tein wouldn't work. FYI, I am looking for the minimum amount of lowering (Tein Luxury Master H.Tech). Opinions?