If its the light 70s one, vertical intake, two weeny screws ,
they work rather well .Little ribs below exhaust port ,
usually a bolt hole over and under cenre of exhaust .
and / or lugs fore and aft. Take a .35 silencer .
------------------------------------------------------------
Theres a 19 the same but 1 fin lower , thats a howler
as the holes are the same size and the timings hotter.
----------------------------------------------------------------
Like Nitro , will switch / change tone . 9x4 if its lugging.
these are the one piece case ones.NOT the B.B. schnerule.