hey wait a second....why would u want to put a new jet in? are u running too lean? or too rich. do some plug chops. i think freds guide in the articles section has instructions for the plug chops. if it black or dark brown then u r too rich. if it is white then too lean and if it is coffee brown then its just right. are you four stroking at top speed? this is when you are going with normal engine noise then the pitch starts to get staccato(drop in pitch and is chopped up) if this happens then you are runniong too rich at top end and u need a smaller jet.