On another thread I saw a need for a new fuel rail. why cant RC Engineering re do

my sizing and I keep the stock fuel rail with a Cartech regulater?

 

because it just don't work that way. not when you want to use big injectors.

 

because the 1600's are top feed injectors while rc takes stock 850's which are side feed and bores them out to 1300. soooo 1600's need a new rail to make them work while 1300 since they are really stock 850's fit in the stock rail