Call Hagon in UK (0208 502 6222) and tell them your details . I got 340 mm (stock is 320) which they said is the more common order for R3. Really helpful and they'll take your order on the phone. From Order to on my bike was less than a week. Am I happy?... See my post from yesterday on bearclaw corner called "I dont know why Triumph dont"
What would be the acceptable clearance to shorten them? 310, 300?
And thanks for posting this review. It's probably gona be the next thing, you convinced me. Did you install them yourself or paid some place in the GTA?
I've never tried different length so would not know. My biggest item I was trying to fix was how much the backend moved in turns. This drastically improved this issue but also made the bike so much more comfortable.
You can do it yourself pretty easily. For the right hand side I left it on the stand and used a car jack to slight take some weight off the rear end. Hand tools on and off. When you are putting it on use the bolts to push it in flush vs trying to push it in by hand. The hole is pretty tight and this makes it easier.
For the left I had to use a couple of used tires to lean the bike on simulating the kickstand and do the same. No problem doing this by myself.