FMF exhaust question

[fat guy]

JUST GOT AN FMF POWERCORE IV SLIP ON, STILL RUNNING STOCK HEADERS, FILTER, AND FACTORY CARB SETTINGS/JETS. I PUT THE NEW SILENCER ON AND BLACK SMOKE CAME OUT WHEN I HIT THE GAS... WAS WONDERING IF I NEED TO CHANGE SOME CARB SETTINGS OR WHAT? ANYONE ELSE HAVE AN FMF EXHAUST SYSTEM-- DID YOU CHANGE ANY CARB SETTINGS? (BRAND NEW 02 400EX BY THE WAY, RED BECAUSE RED IS PRETTY) JUST WANNA KNOW SO I DONT RUN IT AND BURN UP A SET OF RINGS OR SOMETHING.

Up the main jet at least 1 size maybe 2,,if ya can take off your airbox lid and jet it even higher for more power. Throw a 40 pilot jet in there too, for easier starting while your tinkerin with the carb.