Just bought my first cadillac and looking for advise

Hey guys brand new the the forum and the caddilac brand.I have owned my black on black 08 cts 4 for about a month now and i have already started to mod it.The caddy came with eibach lowering springs,volant cold air and tinted windows and i just ordered up an E&G prepainted spoiler.But now i am looking at getting a set of after market rims and possibly a new grille as well,I have been looking at 11- 13cts-v black chrome rims or lexani R three wheels, does anyone run either of these and if so i would love to see some pictures and what you thought of them.I was also wondering what many of you have done for alittle bit better performance, I have been looking and i havent found much in the way of parts for a 3.6L with AWD.I was looking at maybe adding a catback set up and possibly a custom tuner but i havent seen much yet for parts on either.And do any of you run an aftermarket system, I really like the stock bose stero but i need alittle more base so i was thinking about adding a 12in sub but i am unsure what is required when adding the a cadillac sound system.I have been into modding cars for about 7 yrs now and i have a very heavily moddifed convertible mustang which i drive when i feel like driving agressively:lildevil:
But my caddilac is going to be my daily and i am looking to make it alittle bit more unique and maybe a touch faster would love to hear what you guys would recommend.