Wandering if anyone can lead me in the right direction. I just put a yosh rs-3 full system with a pciii usb power commander and a K&N air filter on my 05 busa. I loaded the 312 map from the powercommander website that says it's for an 02 busa which was all I could find at the website for the yosh system with the aftermarket air fliter. My problem is after doing all this to my bike it's back firing at the lower rpm range (1500-2500 rpm) usually when I'm down shifting from 2nd gear to 1st gear and it's never done that before. Any help would be greatly appericated.
Removing the PAIR valve should stop your backfiring. BDE (Brock Davidson Enterprises) makes a really nice removal kit and it is a simple procedure.

Pair valve mod will take care of your problem
I have basically the same setup as you (check in my signature), and i had the same problem at first. I installed a TRE (not knowing there would be that effect) and the problem was totally gone...

My $0,02

Thank you so much for your input and insight into my backfiring problem. I'm going to try the marble mood Sunday when I come back from AL visiting friends with the wifey and post the results after a nice Sunday ride down here in GA.

The marble mod worked fine. No backfiring over the weekend ride with the fellas to macon,ga. Thanks to all of you for your advice and help.