The bike has its stock pipes installed but they were definately altered to sound louder than stock. I don't know what what was done to the pipes and I'm sure no re-mapping was done to compensate for the pipe mod.
Sooty pipes? Have you pulled the plugs to check how they are burning? Just a thought.. Someone asked me why I change my plugs every other oil change and I told them because I pull them to inspect them I might as well change them since I had a bad plug that was not that old one time that caused me all kinds of headache. What caught my attention here is you mentioned that you had stocks that were modified. This is touchy and may get more comments from some of the more experienced performance riders that know more about it than I do but I know that after modding my stocks, I was TOLD to disconnect the O2. Nope, it ran too rich. Plugged back in, good milage and still on the rich side at lower RPM but my overall burn is looking good. About to pull the plugs after 1000 miles post mod and see what I got.
My bike idles at around 8-900 RPM's and I up shift between 3K and 3.5K RPM's and cruise at around 2k to 2.5K. ...
I have also noticed that if I rev the throttle after it has been idled for a few minutes that the idle starts to cycle between 900 and 1200 RPM's. This is with the engine warm.
Well you might not think but fix this first. Follow RICZ lead and adjust that idle to 1000 +/- 50 and I try to stay at 1K or just a bump over... Don't have ANY issues with a blip on downshift but your shifting RPM is on the lower side from what I have read and use. These motors like that 3500 band it seems....lol.... Not sure why either my V92 or V106 are so temperamental about the idle RPM but they are. KevinX explained it one time so I took it as gospel and no more issues.
Next thing that caught my attention was reving at idle then getting erratic idle. Should NOT be happening and most definitely NO blipping during warm up. Tricks the computer and fouls the plugs on this system. I am no way trying to stomp on your experience, just point out headaches I have resolved or read about that were resolved concerning problems like yours... May EVEN be a LITTLE guilty MYSELF... As per Lloydz start up recommendation,
Before hitting the button I roll the throttle slightly (about an 1/8 rotation) than I hit the button, once to life I like to hold the rpm's between 15-1800 Rpm's for approx 30-40 seconds if the bike is real cold (50 degrees and below) and 15-30 seconds if were above those temps
Here is the link for more tech tips:http://www.lloydz.com/techtips.asp
IMO, your shift RPM is good, 2200 is about as low as I go but to each is own. If I blip on downshift it's to save rear tire wear along with front breaking before someone chimes in about that lol.... Im with Goatlocker on both his points as you could have a hard mechanical issue however bringing the RPM back up to a lower gear is not a bad practice. BBob is dead on about both the battery and ALWAYS checking those terminals during your monthly inspection or what ever you got set up. My new VV, 3200 miles now... guess what, neg terminal slightly loose. Causes all kinds of headaches with the computer. Last note, and just my opinion, select your octane as per Lloydz and KevinX. I did, again... I blip, no issue, plugs are clean with a great burn. I match ambient temp to my octane.
Hope some of this helps. Before I took it to the wrench I would adjust the RPM, change the plugs, run a 1/3 can of Seafoam through the tank to see what you got. Just my two cents.
@ Gulliver, I am not prone to agree with what you got as being "ok" but that is my opinion. Post more data as the OP did and get some fresh input.
Safe ridin and post a followup...