Post a link to the ones you are looking at. There should be the 555 which is a regular radial and 555R which is a drag radial. There is also the NT05 and the Invo which are great but don't last as long.
If you are looking at the regular 555s, I STRONGLY suggest you also take a look at Mickey Thompson Street Comps. I have not been impressed with Nitto tires when I have ran them. I got better performance out of some BFGs I ran in my 98 than the Nittos.
2000 Mustang GT Steeda build #48. Bolt ons, suspension, Novi 2000.
Just because I give you advice, doesn't mean I know more than you. Its just means I've done more stupid ****.