well this was the first time that John (STRAT DELUXER) had done a Sparkle Drive mod...he basically boosted the gain, and he adjusted it so that you don't lose the low end..basically the same thing that he does to a tube screamer, but he added a new switch to mine since Voodoo Lab uses some crappy switches ..it's already true bypass, so he doesn't have to do that, but he changed the chip out to the TS808 chip, which sounds amazing....but he left the EQ and the Clean functions alone, just messed with the gain. I'm not sure how it differs from the Keeley, but I'm amazed with John's work..he's also modded a TS9 for me, and I LOVE it...he's amazing