Well, I guess I'll jump in here for everyone...
If you are planning on running BFG's on a Cobra then good luck!
You will find them to be like being on a skating rink and many here (including me) have been through that experience in the past....IMHO, just plain dangerous.
Now, if you are putting them on a heavy car like a Galaxie, Chevelle etc then they are great. Do a search on this site. There are many threads that will explain what I am talking about.