Yes it is not legal.
Is it illegal for any kind of roll cage or just because it is 6 points ?
What about a 4 points ?

Eh what the actual f lah........... roll cage was meant for SAFETY -.- car inspection at its best
Safety eh...unless you're wearing helmet and harness then its dangerous...
if its 2 seater then it can have pop-up roll bar (originally installed)...
there's so much variation...installation, mounting point, padding, size location...
it's easier to say, no...
buy satria neo clubsport..got roll cage...approved for street use.. :p
the reson why i want a rollcage is because i wanted to install a harness
installing a (or pair) of harness doesn't need rollcage....
just fabricate proper hook point at suitable mounting point such as seat screw point and rear seat seatbelt point....