is there any significant difference between going from two to one directly after the header and running single all the way out, and running dual pipes all the way back and necking down right before the final muffler?

 

Not really.
Weight and space is a minor issue with a long primary setup.Longer primary runners can maximize the torque curve, but gains depend on your setup.A mostly stock engine wont see much gains over a short primary system.

 

sp12a, yaw carb, carter pump, holley reg, rb roadrace header. would it be better to keep it dual all the way?

 

Streetported motor will benifit from the longest primary possible, my 12a sp, nikki carb with dual all the way produces 130rwhp, if that gives you some indication .

Regards Sue

 

If you've already got the roadrace header and can afford the extra presilencer, go with the dual system. If you're skipping meals to afford this whole system, I'd go single and at least eat some ramen.
But, yes, you should be able to notice some difference between the setups.

 

thank you.

 

What about exhaust scavenging? You'd lose that on a true dual setup...
Are the gains worth that?

 

so do you recommend going with long primaries then tapering to a single muffler at the end?

 

what if you ran dual pipes all the way back into a n1 style duals so you never collect the pipes at all

 

Yes.

 

thank you, again.

 

damn double post