exhaust performance

i've got a PC r304 shorty and i recently was reading around on the PC site and came across some silencer repacking. In the add it said that if your packing is blown out, your bike will seem slow and sluggish. To make a long story short, i have had some problems lately with my bike being SLOW AND SLUGGISH but i just repacked my silencer. The kick is that i didnt repack it with the PC silencer repacking but rather with some household fiberglass insulation. Could this be the simple explaination why my bike is not pulling through each gear like it used to? its obvious that the silencer was originally packed with the PC stuff, so will repacking it with some insulation really affect the top end of the power curve? :|

Thanks in advance. :p