They are both SQ trim blowers, S for the trim level and Q for the quiet S trim. I really don't know what the V-2 or V-9 mean specifically but the V stands for Vortech and I'm under the impression that the -2 and -9 are just some sort of production number(I could be wrong). The A-trim was thier first blower and it is the V-1 A.
You will notice that the cobra has more boost and I believe that this is due to the compression in the engines. We want reliable combos and the cobra can handle alittle more reliably than the ls1 because the cobra only has 9.85:1 compression. You add an aftercooler and you can add more boost because it cools the charge and the heat is what damages an engine(burnt pistons and/or blown gaskets).
Then again, maybe it has something to do with the extra 1000rpm the cobra has on the top end.. but more boost is always just a pulley away
