exhaust "whistles" at 5K and up rpm

ok here is a weird one for you guys. I have a magna flow exhaust with 2 1/4 inch piping form the catback. now at about 5k rpm it starts to whistle…really loud… sounds like im screaching tires. Its kinda cool but is it hurtin anything? Im thinkin it maybe the tip i have… its a dual 2 1/2 tip. does this happen to anyone else?

ANYONE?..or is this normal?..:confused:

my HKS Sport i noticed kind of made a “woosh” (like an airplane jet) when i got to mid rpms when i first put it on… it felt real smooth. :stuck_out_tongue:

i know intakes have a tendency to whistle at when you get into the high rpms