I found some seats for sale for a 911 gt3. Will they bolt up and plug into the 997 tt?

 

I'm not aware of any difference in the floorpan that would stop you doing this, but remember that depending on the GT3 Seats you have seen, they do not all have the ability to fold the back forward to gain access to the rear. You may find too that they reduce the rear seat package space.
Regards Big Bob