20,000 miles is a fair bit on any bike but it's not excessive for 5 years no.
I've been known to do 9k in a year and thats by just riding on the Isle of Man!!
If the price is right go for it.
45mm Termi's are the standard size for the 748, so they'll fit straight on, where as for 50's you'd either need a full system or an adapter.
Threaded Mode