This pedal is just about the best Tubescreamer style clone I've ever encountered. It's more of a TS808 than a TS9, but it has WAY more flexibility than either of the pedals put together. The boost function is independent of the overdrive, and sounds great by itself. FYI, boosting single coils or coil-tapped 'buckers gives a FANTASTIC rhythm tone for funky barre chords. The overdrive side is good in and of itself, but being able to blend the clean tone back in just takes this pedal to levels unknown. This won't do metal distortion, but it will everything from soft 70's rock to hard 80's rock, Classic Rock to Alternative, and everything in between. I'm not sure if the boost is pre overdrive or post, but it sounds great regardless. This is definitely one of those pedals that makes you think "I love this and it will probably stay on my board forever... but even if I decide to take a break from it for a while and use something else, I'm not selling this thing!"