Removing an ASP

I recently did a changeout of our disks.  There were 8 small drives in ASP 1 
and 4 larger drives in ASP 2.  This layout worked perfectly for what I needed.  
Now, I have 4 big disks in each ASP.  There is only one parity set.

I am noticing performance problems and I would imagine it's because I only have 
4 drives in ASP 1 and am experiencing disk contention.  I'm sure that if I had 
only one ASP and all 8 drives committed to it that my performance would greatly 
improve.  What would be the best way to do this?

I know how to move libraries from one ASP to another, but the question would be 
how to do this and move drives between ASPS.  Is this a DST or SST function?  
Do they have to move as a set of four at one time, or could I move one disk at 
a time?  If they have to move 4 at a time, then either I move the libraries 
beforehand and then restore -or- I do a save and restore of everything in ASP 2.

What are your recommendations?

Bill