2004-2007 Cadillac CTS-V Performance Mods Discussion, Mp122??? in Cadillac CTS-V Series Forum - 2004 - 2007; I know there was a thread on the MP122, but I can't seem to find it. A little help would ...
I only know of Jesse, he owns wait4me performance and is a sponsor who is mostly on the V2 Forum, putting a MP 122 on a V1. Talk to him, as he is very knowledgable. One of the primary concerns is hood clearance, and boost, as you are paying for more power but can a stock motor take it---I say so, buy many think you are done on a stock LSx motor at 8-9 psi.
You should be able to run 9 psi on the stock motor as long as you have a good tune.
IIRC, 10.5:1 on LS6 and 10.9:1 on LS2. Many C6 owners have 12psi and higher on stock internals; most run a meth kit also. Good tune and good fuel are the key. Most V owners with Maggie have nothing to worry about, as you probably are at 6-7psi with the 2.8" pulley.