I have a 2003 YZ450 and I am contemplating adding the proper parts to the carb in order to enable the ACV (air cut valve or coast enrichener) circuit. I have read the posts that say this circuit makes tuning more difficult, but I want to see if I can improve the popping on decel. Anyone have a newer FCR and can measure the drilled hole sizes? Any other parts needed than what is in the picture? Lastly, I will need to figure out a way to find or make the brass insert.