Kind of flared? Makes a big differece in how its flared and the type of flaring since it directly impacts air turbulence inside the port. In turn the amount of air turbulence creates colouration, frequency artifacts and other port noise The vortex flared ports in the EP subs are very quiet from what I've heard so I wonder if indeed there is a problem with your port.
A slot port design can be effective if its flared at both ends and all edges are rounded. Flares help by compressing air into the body of the port inside the sub and expanding it upon exit.
The problem of internal edges also needs to be addressed. It gets more expensive but the slot can be very effective if its edges are rounded and its flared. In effect flaring and rounding edges increase laminar flow causing the slot to behave much like a cylinder. Most slot ports I have seen are not rounded on all edges or have minimal rounding or flaring which makes them noisier than cylindrical ports.
By the way there is also turbulence inside the cylinder port which is another reason why vented subs will always have a characteristic bass sound compared to a sealed alignment. Its just a heck of a lot less than in an edgy slot. I've put my ear against a lot of ports. No question about the audible difference between an edgy slot and a flared cylinder port with similar area openings. Its the primary reason I have always passed on subs with slot ports.
