I have ran a through a lot of searches and found a lot of information, but I do not see information on the Stock STS Wastegate Spring.

To summarize:

The Stock STS Wastegate looks to be 38mm.

With the Spring options being:

PSI COLOR
3.6 Small Yellow
5.8 Small Red
7.25 Small Green
8.7 Small Blue
10.1 Large Yellow
11.6 Large Red
13.0 Large Green
14.5 Large Blue

We can combine a large and spall spring to get the addition of both in the resulting boost pressure.

Is the Small Red the spring that STS puts in the Wastegate in the basic kit?

 

Most STS kits are designed around the 5-8 PSI range so they usually ship out with the 5.8 PSI(small red) WG spring. My Silverado and Hemi Ram both cam with the 5.8 lb spring but I bought the 3.6 one so I could cruise in low boost then switch to high boost using the boost controller.

If you go to the Tial web site you can see the exact WG that STS uses and buy different springs if needed. It might have more info too.

http://www.tialmedia.com/documents/w3_tial_38_sp.pdf