If you're getting slip-ons only (keeping the stock header) then there's probably negligible difference in performance and weight between the various offerings, and you don't need to re-map the fuel injection no matter which slip-ons you choose. You will benefit from re-mapping the fuel, but it's not necessary.
A difference in a few pounds in weight between different options doesn't really make a difference on a 640lb bike. For example, my Remus Hexacones weigh about 7 lbs. less than the stock cans. That works out to the equivalent of gaining about 1.3 HP at the wheel; about a 1% gain.
It would also be pointless to compare dyno results from different people with different exhaust because the variations of different dynos, bikes, elevation, temperature, humidity, etc. at the time the dyno pull was done affects the results. The only way to get a valid comparison would be to try all the different options on your bike and get each option dyno'd at the same shop.
That simplifies your selection criteria down to looks, sound and price. In my opinion, price should take a back seat if possible and instead just determines when you can get the exhaust. When I spend a big chunk of money on an addition to my bike, I want to be happy/proud of it every time I see it. I would hate to settle for something I like less knowing that I could have saved up some more money for a few more months to get what I really want.
If you want to go for the biggest impact on sound and performance, you would want to look at a full exhaust system. You can either go with the Muzzy 4-into-1 system (I think it just looks wrong to have single exhaust on the FJR, but it's the most weight savings available), or the Holeshot 4-into-2 system. With the Muzzy system, you must use the Muzzy muffler. A couple different brand slip-ons will fit with the Holeshot header with no modification, but others will require their mid-pipes to be expanded a bit to fit. If you go with a full system, you
must re-map the fuel injection.
Now, I will share some data:
Titanium Remus Hexacones cost about $1000. I was able to get a deal for about $940 shipped. They come with a removable baffle that muffles the sound a bit more. I ride with mine out.
Weight
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Stock header: 11 lbs.
Stock header with catalytic converters removed: 9lbs.
Holeshot header: 10lbs.
Stock muffler: 10 lbs. (x2 -> 20 lbs. for both)
Titanium Remus Hexacone: 6.5 lbs. (x2 -> 13 lbs. for both)
Sound (idle & rev) - click for audio sample
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Stock exhaust:
Looks
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Stock mufflers: Acceptable
Titanium Remus Hexacone: Frickin' Awesome. See below. The six-sided shape of the mufflers looks right at home below the six-sided shape of the side cases. Plus, a bit of carbon fiber and titanium on the bike is always nice.
