I Preffer the last two.

i have also spoken to a few tuner here in the uk regarding the swap from 2 pipes to one and there advice is below.

HOLESHOT RACING
[q] why dont they do a single as standard and will it be ok
[a] The 2 stock ones are for cosmetic reasons and noise.
It is harder to make 1 single pipe as quiet.
No noticeable difference in power.
A few race bikes keep both cans as have to follow standard silhouette of the bike, but years ago gsxr1000 were 2 pipes but ony using 1 and 4into 1 and same on yam, Honda sp2 ,etc.
It will be fine


BIG CC RACING
[q] I wonder if you can help, I am considering converting my 2008 R1 from usderseat exhausts to a single side exhaust. Would there be any problems caused in this tuning wise? There is a big weight saving to be had
[a] We could map it for you yes. I don’t foresee a power issue with it, if anything it may help

 

I had comp werkes on my 1098s duc and it sounded amazing! liked the sound better than the 2011 ti termis i have on my 1098r now.i can only imagine what it would sound like on a shorty style side mount on the r1...as long as you like loud!

 

was the build quality good???

 

I really can't stand the look of the FMFs but I gotta be honest, a single sided FMF would look really good IMO. It's just kinda, well, different. I think I'd like it if I were into the single-sided deal. I better get outta here before people catch me dropping compliments on the FMFs. :vanish

 

I would stick with the undertail exhaust unless you are planning on doing some custom body work on the tail. These bikes look retarded with a fairing formed for an exhaust that isn't there.

 

undertail wll be sorted, dont worry

 

Interested to see how this build will go.

 

I think the first one is badass