I put new springs on my white car when I did the cam, and took everything back out after ~8k miles. I know that boost used to increase at upper rpms, but I don't know for sure if that happened right away when I did the install - Can't remember anymore.

The LS6's on my 01 were bad though...boost would always increase 2-3psi at upper rpms. Now with the 130's, boost stays the same across the entire rpm range.