Fitting more capacitance into the X-Can V2
This is probably one of the most worthwhile mods you can do to the V2. There's not a lot of room inside the enclosure so you won't be able to fit huge caps (unless you rehouse it in a new enclosure) but you will easily be able to fit 1600uF caps on the top board. There are 8 x 1000uF and 2 X 470uF as stock on the upper PSU board....... these can safely be replaced with much higher capacitance.... I fitted what I had to hand (some 2200uF and some 1600uF) and they made a big improvement to the sound quality.
Replacing the non polar output capacitors
These are 6.3V 220uF non polar types. They can be replaced with 470uF non polar caps for greater bass extension and improved sound overall:
Replacing the 10uF input capacitors
Surprisingly MF fit 10uF "polar" electrolytic capacitors in this position. These do not sound good and can easily be improved on by replacing with 10uF "non polar" electrolytics as there is no DC across the cap. You could also use 10uF film caps or bypass the 10uF non polars with a polypropylene film cap
There are a couple of sources for Non -polar caps in the UK