Dont know much about the ITBs I am more of a boost head

IMO the phantom is not worth it if your going to road race all it is really is a big spring
I would get a itr tranny or instal an lsd in the tranny you have you can get one for around 500 and up check with ICBmotorsports

cost wise depends on how far you want to go I know the ITBs run a grand to 1500