what are my choices and where can i get them?

You can get the UTR 1 Roof Spoiler or A Carbon Fiber one.

The Carbon Fiber one i found here on Ebay.
http://cgi.ebay.com/ebaymotors/03-04...5746QQtcZphoto

And another I found on Ebay
http://cgi.ebay.com/ebaymotors/Infin...mZ120074997604

Here is a link to a thread talking about Roof Spoilers...Good Luck..

https://g35driver.com/forums/showthr...t=roof+spoiler

edit: NVM ^ this guy beat me too it