I have a 6" SW mod 29 in .44 that I had Magna Ported, the gun was basically unshoot able without porting, with porting it is my favorite sidearm.
I have not noticed more "report" or "muzzle flash", having said that the holes or slits that were cut in the barrel were very slight. I have noticed especially on automatic pistols that the ports are huge which probly accounts for the back flash and seeming loader report.
I don't know if magna port is still in bussiness but if you have a gun that needs to be de-kicked try them they did a great job for me.