I'm all for modifications but I agree with Biblio,
Check here,
https://cx500.000webhostapp.com/SV650Carb_Balance.html
If a user wants to add a spigot extender they must allow for the extra tube length in their calculations e.g make sure when connected to the,"Balancer" both tubes are of the exact same length otherwise they will get a false reading and never be able to get a correct balance. Also the tubes need,"Restrictors " in them to stop balance fluctuations.
The,"Carbtune 2" I bought over 15 years ago is still one of the best made quality pieces of kit I've ever bought and still like brand new and so easy to use.
http://www.carbtune.co.uk/carbcust.html
HTH