New battery cures backfires?

[Rev]

08 KLR, DG exhaust. when I bought it it was not rejetted for the pipe, so when it went in to be fixed they rejetted it free, per DG's advice. I got it back and backfiring during engine braking was reduced, but not eliminated. I noticed it get progressively worse since I got the new top end, and also notice the bike getting harder to start and needing more choke to get started. Well, occasionally the bike would just click like the battery was dead on startup then fire over fine.

Well today the battery went out completely, and come to find the battery was dry. dealership put a new one in for free, but i want to get a sealed gel type so i dont have to worry about it anymore.


but now, after driving it around for an afternoon, ive noticed the backfiring has almost been eliminated. im not looking a gift horse in the mouth, but what the hell? reasons?