I believe the internal diameter of Renthal clip-ons is 16 mm.
The heaviest compatible universal bar ends available are the HVMP ?Heavy? bar ends for ?Rethal, Woodcraft, Rizoma ...?.
These weigh 416 g each.
http://www.hvmp.com/14mmUniversal-s/46.htm
The Oberon ?large? universal bar ends are what I am ordering today.
The weight is 254 g each.
http://www.oberon-performance.co.uk/acatalog/Motorcycle_Small_Universal_Bar_End_Weights.html
I am currently using a lighter set of universal bar ends (155 g each), with the same metal type fitment to the Oberon?s. This attachment type is very secure, feels akin to the threaded OEM type and even though they aren?t overly heavy, the difference is night and day to the nylon caps typically found on race clip-ons.
One thing to note, is that HVMP are considerably more expensive than Oberon, partly due to shipping costs from the USA.
For what it?s worth, I am loving the Renthal Gen 3 clip-ons for road use, purely because I have the bars in the correct position for me and thus I find them to be far more comfortable.
As we discussed though, you will need to keep the steering bump-stops in order to avoid front fairing clearance issues