So, recently just purchased an 07' V6 convertible. It's my understanding that they come stock with 16 inch rims, correct?

I want to put some nice black bullits on there, but having to replace the tires AND the rims is quite expensive(and the fiancee won't approve it more than likely).

Any suggestions?

 

Yes, your car comes with 16" wheels.

The closest we would have would be the shelby torq thrust M wheels in 17"

 

Either leave stock or get some bigger rims. Theres a lot of places you can get deep dish 18s for pretty cheap and find a good tire pack. Save up some cash and let the fiancee know what you want.