givanni_919, I'm going to wade in here because I had the same concerns. I perused the many threads on the old forum and with my own experience with my '04 919 came up with the following statements (I believe facts).
1. The ability to detect and accept exhaust smell runs the same bell curve through the population of owners as most other things. Some are very bothered by it, some realize it is there but don't feel like doing anything about it, and some can't detect it.
2. It is generally caused by the position, length, and attitude of the exhaust openings dumping exhaust near to the rear portion of the "vacuum" created by the rider's body and the bike itself. The exhaust is pulled in behind the rider (worse for a passenger) where it stinks up ones clothing.
3. Many things have been tried to alleviate the condition. All the attempts including changing brands of gasoline, additives, brands of oil, adding a PCIII, etc. make small changes to the equation but almost never has it "stopped" the condition entirely.
4. The only "sure cure" is to redirect the exhaust stream. Some have found success with the stock system by adding extensions to the mufflers -- most have a negative impact on asthetics as they look like they were borrowed from a Peterbilt. These have the ability to move the exhaust stream farther rearward, hopefully behind the vacuum, and to possibly direct it outward, to the sides, rather than directly to the rear, or worse, to the centerline of the bike.
Now, some are going to react by calling you a wimp using words like "get used to it" and "deal with it". These guys, smelling they way they do, will never work in my job. Some of these have realized the stink exists but have no power to effect it so they bluster their opinion since they are powerless to change it. They are not willing to sacrifice the asthetics of their mount to solve the problem. There are a few who truly like it! Then there are a few like you and I who will not tolerate it.
I not only could smell it on my clothes, I could actually smell it sometimes through my helmet while I was riding! I was not willing to intake any more carbon monoxide than I already had accepted just by riding a motorcycle!
I made the only ebay purchases of my life and bought a used '95 CBR900RR header and a Wileyco carbon fiber can and mounted them. Problem solved. I sacrificed the more asthetically pleasing (to some) high mount duel cans to the older (yet still appearing on many bikes even for 2007!) single side mount. One thing I found I like about the CBR header are the curves of the individual pipes coming out of the engine block. I never like the stock pipes with their "rain gutter drain pipe" look.
I spent less than $200 for the whole changeover. If you buy the system new from Honda, it will run you well over $1000. I had the header sandblasted to remove dirt, rust, old finish, etc. then painted it myself with a can of high temperature paint from Walmart -- two coats, and it cured nicely, is easy to clean and the black color looks good to me.
I'm not advocating you follow my lead here. Do what you want. ...but it solves the problem decisively and without further experimentation. It is certainly reversable since I kept all the old exhaust parts.
Good luck to you and let us know how it comes out.