Magna-porting does reduce recoil, but it does increase noise. Muzzle brakes are more effective at reducing recoil, but are even louder.
When I was younger, I had muzzle brakes installed on about 7 or 8 of my rifles. It's not a problem when you are at the range with ear protection. However, if you do not use hearing protection when hunting, the muzzle brakes (especially certain times) will make you curse and swear in pain.
I no longer like muzzle brakes. I agree with Redhawk, just get a recoil reducing butt-pad. It will not be as effective as a muzzle brake, but I prefer it nonetheless.
Trust me - this is coming from someone who made the mistake of having muzzle brakes - and magna-porting is almost as loud.
Zachary
Zachary