No... its not normal to sound like that.....Sounds like the flange where the Powerlog and Crossover pipe meet is leaking. Hold your hand close, but not too close the the flange as the car is running, see if you can feel any air against your hand. If so, turn the car off, and retighten the crossover bolts. Turn one 3 turns then the other 3 turns... keep going till both bolts are tightened. This should solve your problem.