I just bought a 97 ex from a little car lot and my first question is i have the stock 14 inch rims n it says to put 185/65's on it and it has 185/60's would that throw my speedometer off any? and it has a cold air intake from inside the fender and a skunk2 intake manifold and aftermarket headers i think they are pnx or something like that how do i know if the whole exhaust has been upgraded or if the cam or injectors have been??? and what else could i do to this thing to get more hp's this is my first honda

Thanks
Brandon