I am the OP, and I just came back from my morning weekend ride. I started out with the DB killers installed. For some reason, the loudness and the sound so much resembled my stock exhaust (drilled with 7/8 holes) that I had on just until yesterday, so I couldn't stomach the fact that I paid $600+ for something that pretty much sounds the same to me as a rider...
Needless to say, I removed the DB killers and continued my ride. That said, I'd like to say that I am kinda getting used to it, and I love it! It is loud, alright, but it's not as annoying as those Harley ear-piercing sounds.
Last night before going to bed I adjusted the CO levels (procedure is described in another thread somewhere in this forum).
Impressions:
1) First of all, no backfiring whatsoever.
2) Idle is still hunting (kinda resembles v-twin sound)
3) Going 4k in 1st gear, I opened her up: the front came right up! Before installing the Leos and adjusting the CO levels, I used to do this very same thing probably tens of times on each ride---never once the front came up before! If I wanted a power wheelie before, I'd have to close throttle for a second then open it up, and only then the front would lift. Well, now it's just doing it without any tricks or anything. For me, this is true indication that the bike is more powerful! Don't know if it's the Leos or the CO or both, but it is a lion now!