A set of the 4" baffles can be had on ebay for $9 total from shotglassx83. I've bought 4 sets of them from him. I usually get them in two days!
Anyway- running rich doesn't harm the engine, it just wastes fuel. There is a finite amount of O2 to mix the fuel with. anything above 14.6:1 just fouls plugs and goes out the pipes. Running lean, on the other hand, will harm the engine (i.e. burnt valves).
Dogg is spot on about the back pressure causing a loss of low end torque. You need some. I've got some BUB's, a set of fishtails, had D&D, have a set of Khromewerks short $30 turn-outs, and have had a set of JCW turn-outs, as well a a few sets of stock pipes in varying stages of de-baffle up to and including a set that are nothing but the cans- so I have experimented with pipes and baffle quite a bit.
My experience with the open totally dissected (baffles, screens, packing, reducers,- everything) would be identical to your gutted BUB's. I put one of the 4" baffles in the header and ran them like that for a couple of days. Still silly loud, and the tone is not good. Still has that hollow ringing metal sound. Also, the BUB's out perform that setup. If you are going for performance, the stock BUB's will be hard to beat. They are designed for that bike.
You might try some things. Nothing has performed as well as the BUB's on my bike, purely from a performance standpoint. But, I don't care for the looks of them. I REALLY like my fishtails, and have spent hours trying to tune them to perform like the BUB's. I have two sets of the 4" baffles in each side; one at the end of a 22" straight extension piece and another at the exit of the 'tails. At first it was way too much. No power at all. So, after much experimenting (remove the front set, turn the front set around, cut the front set in half and try it both ways, open the center up, etc.) I ended up with two in each side, but ran a 3/8 stick of rebar through them to "open them up". Seems to be close to the BUB's now. A little less low end but a bit more "snap" on the freeway. Has a nice sold idle note and will still give off that fishtail "crack" when you hit it.
I'd try the 4" baffle or maybe the 8" and cut it off (8" won't fit up the header, only about 6" will). I like the beer can baffles better than the stock reducers, even if you run them straight. Just cut the flaps off and you now have a high flow reducer!
