this topic is too wide, it doesnt make sense
if someone is to reply properly, it would take few hundred pages , A Whole Book to explain to you everything
either you got to live it thru experience or u got to read alot alot of books , i choose experience ,
first of all diffrent cars have diffrent upgrade path , turbo cars , n/a cars , supercharger cars,
the basic mods are pretty similar, bt the following paths are totally diffrent and no one can teach you that in this forum in a wide topic like this, if you do pint point "EVO V upgrade advise" , or "Sentra Upgrade path" , then there is a wise anwser hehe
ohh ok, if u say unlimited money
then i would say transplant a V12 BMW halfcut , put 4 turbochargers , hhuhuu here u go 1000hp++ car ,
errr please be more specific bro, if not u r not getting anywhere :P , everyone is jst gonna make fun hehehe, dnt be shy to reveal wht car u have