In regards to possibly running rich-fuel trims and AFR with the Roto-fab are very close to stock, so your car shouldn't be running rich. There was a great deal of R & D to make sure the AFRs and FTs duplicate stock numbers as closely as possible.
With driving habits remaining the same, we typically hear there is a slight improvement in fuel economy with our system. However, there is a natural tendancy to use the pedal a little more when the sound is more pleasing to the ear!
Until the OP contacted us, we didn't realize anyone had a problem with breaking the top off of the breather canister. For those preparing to install, press the release tab on the top factory connector all the way in the direction it travels. With the lever fully depressed, pull straight upwards to disconnect from the canister. Sometimes it helps to push downward on the fitting, then pull straight upwards. Remove the canister from the air tube after you have removed the inlet elbow from the car.