The best solution is to change the header from conical type to non conical, and go to 6 fin header.....youŽll manage to get 5:30minutes at best.....all modern engines are fuel suckers...another option is reducing venturi size from 5.5mm to 5.0mm, but power gets hurt but being more drivebable.
Afm
Thanks for the info.
Would going from a
5 Fin Conical to 6 Fin Conical make enough difference with fuel saving.
Or should I go from
5 Fin to 6 Fin Non-Conical as you suggested.
Ive had a look at the pipe. It says Novarossi Italy, but I cannot find a number on it. Perhaps it isn't a 2660 pipe. Just read that they was the recommended pipe.
Also there is no number on the manifold.
So the manifolds are designated Conical or Cilindrical (=Non-Conical).
Cheers