no offense, but convertibles if you want to slow the car down sure go for it... if you want speed get rid of that clunky convertible top and the back space it takes up... saves a few hundred pounds i must say... and looks a LOT better if you ask me :)
i still wouldnt sell a good 300z for a SS tho... my good friend has an SS, i have a NA 300z, after i get my mods i will beat him easy.