Hi again JNS, yes I did replace the K & N air filter with a stock air filter. I'm also looking for a good used stock exhaust muffler as well. Right now I'm running a Two Bros race muffler that came on the bike and I've heard that that might effect the way the bike will run. The PO(s) did a lot of mods to this bike which really messed with the way it ran (or didn't run) when I bought it. Thanks again.

 

Now that is a crazy coincidence, because I was just getting ready to post up some of my OEM parts in the Sale/Trade/WTB area, and one of those parts is my stock muffler!
I didn't really want to sell any of my OEM stuff, being as my plan (dream) was to one day return the bike to bone-stock, once I've got the R1 race-ready, but I NEED money to procure the items I still need for my first Track day and sprint race.
I'll give you first crack at it, before I post over there.
Here it is installed on the bike:





And, in the dining room:



It's very close to perfect - it has one very, very shallow "hairline" scratch, that you can't see when it's mounted. It looks pretty much brand new on the bike - if you are a perfectionist like me, you would probably throw a couple of thin coats of high-temp flat black paint on, before mounting it, but it really wouldn't seem necessary to most folks.
I'm selling it for $75, and shipping to anywhere in the lower 48 is about $15 - PM me if you're interested, and if not, I'll go ahead and post it up in the for sale area.
Sorry about the super-wide post, I just wanted to post a large pic of what it looks like on the bike.
If there are any other OEM parts you're looking for, check for my thread in the for sale area - I'll be adding a bunch of stuff starting this afternoon - if you see in my build thread, that a part's been replaced, then more than likely, the stock one will be available.