I can honestly say that I was surprised at the sound when I did the 2" Fullsac cores. They are a little quieter at idle than the BUB 7"s, not a lot, but running down the road at various other speeds, I can't really tell a lot of difference, maybe a little quieter, but they have a great sound, I am very pleased, and love the look of the 4' stock cans. I will not put the BUB's back on because the difference in the sound is just a little less than the BUB's but not much. And I do have the regular bafles in the BUB 7's. I am running the V&H Power Duals and that probably helps with the sound, NO CAT.