Im talking about the 4 and 5 string with the MEC Jazz PUP's, Not the Broadneck. So what do you think it is? Pickups? Woods? Or the Combination of the two? Im not 100% sure on what it is, But Id say its got to be the pups or pre amp, Cause Ive heard other basses with the same woods and the growl was nothing like the Thumbs, The closest thing to a Thumb Ive heard was a WAL.