If the car has the same engine as the CTS-V then I would follow what they are doing and how reliability has been affected (if at all). That would be a good starting point .. as far as modding ... you know as well as I do once you start it is a drug
I don't believe the LSA is a fully forged engine (like the LS9) so you may have to keep that in mind.
If you are looking at keeping the warrenty, then your choices would be limited I'm sure ...
If not, the sky (and money) is the limit !!