well....not saying your setup isnt good...its just, there's no really a way of telling if that performs aswell on his car. and when u say it increases your HP dramaticly...well what you are feeling might be better throttle response. cuz you wont really know how much HP it gave you, unless you dyno it before and after. and upgrading your header and catback, wont really dramaticly increase your hp, i doubt it will even go over 10HP of gain, maybe in less.
and i'm not sure if V Tec kicks in at 5.5rpm, i remember we had a thread about this...i think it was around 4800rpm? i dunno correct me if i'm wrong.
whatever setup your getting, you have to do all your hw and make a plan of what you gonna get first, next, etc... dont wanan just get watever and slap it on. just cuz there alot of all motor parts other there, doesnt mean all of them will work fine together. check some stuff out, see how it works with your other parts.