was wondering what peoples opinions on exhaust packing for both 2 and 4 stroke applications are.... have a fmf powercore 2 on a CR500 and a bills pipe on a CRF 450. i havnt repacked either one, the 500 has had that system on for quite a while and i just got the 450 a few months ago so im not sure about it. does the packing actually help the motor to function properly or is it just a noise dampener...? ie, should i repack the damn things ?