I've never heard the gr07, but what exactly about the bass response don't you like? Have you tried many different tips?
I gotta say though I find it surprising that the poor pain job got through their QC.
I personally take slight issue with the highs, and quite like the bass with the ports at ~.2 of the way past closed and the first notch. Literally as little as I can while still perceiving a difference. With larger tips than I usually use and a shallow insertion, I'm finding them much more polite and tighter.