i know a have a power core 4 should i rejet or not

 

yes

 

yes definetly rejet i had bought a supertrapp a while back and i did not notice a real big gain untell i rejeted and did an air box mod
if you dont want to do the air box mod i would use a 136 main jet below 3000ft... a 132 if your between 3000-6000...use a 128 above 6000ft
if you want to do the air box mod which i would recommend then use 148 main jet below 3000ft..... a 144 between 3000-6000ft above sea level....and a 146 above 6000feet

 

I put in a 150 in my buddies warrior, hes running an fmf pipe, k&n filter and no lid. We are 42ft BELOW sea level. That thing hauls ***....for a warrior [img]i/expressions/face-icon-small-wink.gif[/img]

 

yes, u always want to rejet when ever u have a performance part added. u need more gas, depending on what part it is. for a pipe i would guess that it should be anywhere from 5-20 bigger main jet. u just go with different jets until u get a nice colored plug. if the plugs black, that means its too big of a jet. so go slightly smaller till its a nice color and ur power is nice