they are ok, its a clone of a vespa made in india so most vespa hop-up stuff applies but some stuff is wacky
there has been quite a bit posted on TFR tuning over the years, you should be able to find some stuff on here if you search, lots of folks out there doing the vespa thing, not so much on the TFR side.
pipe is about the easiest, they already come with a decent 12mm carb so not much to gain there, you can gear them up but vespa engines in general don't respond super well to basic speed mods without a kit.