I'm going to put a cat-back exhaust system (5.7 V8 Hemi '06) but I'm not sure which one to go with, Borla or Magnaflow? I want something with a "growl" but not too loud where it would be annoying...I also want the best "performance" out of it, HP gain, etc. . Anyone that has one of these or knows about them give me your opinion. thanks...