After reading someone else's evaluation of these pickups in a Yamaha RBX170, I decided to give it a go. I have an RBX270, exactly the same model, but quality-wise one step up (different body wood, better tuners). Decent bass for the money, but at that price point the pickups are usually a weak link, giving a somewhat hollow tone and being quite microphonic also. Swapping them for the SD P/J QuarterPounders was a breeze! The manual is clear, but it describes a volume/volume/tone configuration, while my Yamaha has volume/pickup blend/tone. No big deal, just connect the SDs the same way as the original pickups. Now she growls and snarls deeply with a full rich tone, with high output and very little noise! The pickups are balanced very well, the P and J have their own distinctive character but come on equally strong. Tested on a VOX headphone amp and on a Markbass Little Mark III with Peavey 4x10" cab in a band rehearsal. Absolutely no problem cutting through between two Marshall guitar stacks!