there is Jasma badge and somekind serial number and it matched with hks as maker. haha.. yeah you are right. its just 4mm
And matty yes, hks is very very quiet too, little noise when reving. Maybe i was little hoping that nismo makes little more sound than hks... Well. i try and listen. For future, 3.5" would be good. If i can brake 600hp limit sometimes soon.
Or where 3" exhaust is flowing ? 400-600hp? i know downpipe makes biggest difference cause exhaustgas is hot near turbo ect.
now i found it. And sorry, its legal not legalis!
There is only muffler but i've whole pipe.
and here is whole exhaust.