04 450 Exhaust Mod Jetting

welcome to the site as a member, josh. i'm surprised that you would join and subject yourself to potential abuse :lol:
at the left is the owners doc. read up on all the mk2 fcr stuff in there and also do searches on various aspects of jetting. there have been a lot of threads about it. one that i found interesting was "the $40 spruceup" or something like that by buzzard?

Hi Josh

one thing thats not really easy to find stuff on even though taffy has put it in the DOC is the MAJ (Main Air Jet) not the MJ (main jet)

put a #160MAJ in instead of the stock #200. makes life easier for you trying to work out how to get a nice crisp midrange and good WOT peak tourque under load at the same time without the poor girl going lean at high rpm

roughly seems like you want about 5 or 10 bigger MAJ than the MJ ie 145MJ with 155 MAJ, 155 MJ with 160MAJ or 180 - 190MJ with the stock #200MAJ etc etc something just like the little table for pilot jets correlating to pilot air jets. not sure if ive got it spot on but its a start.

once the fuel curve is sort of right its easier to make sense of everyones suggestions.

this site is interesting http://www.factorypro.com/tech/carbkei.html