I like the twin pipe all the way back like spirit garage.  Looks cleaner and tucked up.  

That's because it follows closer the original Nissan design for a twin-pipe system.

Having said that, they sold more single-pipe systems within the JDM and export markets.

The question to be asked is what benefits are there on a stock (and also prepared) engine from a twin-pipe system ? I have my thery but let's hear all yours.

The picture of the red 240z above is the stainless system from Reinhard Japan. It's twin 60mm from the headers all the way through, twin 60mm rear muffler too. 

Exactly - Reinhard and thanks for the extra info.

I wasn't aware that it was twin 60mm which is huge (for specific large cc engine applications ?) and a lot different from Fujitsubos' twin 50mm.

For reference, my single pipe is 63mm.

16 hours ago, Sean Dezart said:

That's because it follows closer the original Nissan design for a twin-pipe system.

Having said that, they sold more single-pipe systems within the JDM and export markets.

The question to be asked is what benefits are there on a stock (and also prepared) engine from a twin-pipe system ? I have my thery but let's hear all yours.

 

 

The twin pipe setup is something that works with an IL6, all the performance bmw IL6's have the same setup.  I guess its down to port scavenging.

should be good for upper midrange?  

Could be right there with port scavenging.

Good from upper mid-range upwards in theory, perhaps logical to fit that with an S20 producing it's power and torque higher up the rev range.

Good therefore for smaller, higher revving engines. Now, is it also good for mild-prepped L28s and strokers ?

1967/1968 Parallel Pipes in Road Test Prototype:

 

 

And a dual exhaust in the 1967/1968 styling stages:

 

 

Nice share  - thanks. No fuel tank on the rolled car ? And the size/shape of that which we know must have defined the single-side exit path.....

1 hour ago, Sean Dezart said:

Could be right there with port scavenging.

Good from upper mid-range upwards in theory, perhaps logical to fit that with an S20 producing it's power and torque higher up the rev range.

Good therefore for smaller, higher revving engines. Now, is it also good for mild-prepped L28s and strokers ?

I've no idea, works on 3.2 ltr cars.

Does it and efficiently ? So, it works on stock cars right through the range - sort of one size fits all.

Can a turbo benefit from having 2 pipes? Seems like you could get more exhaust flow that way (e.g. two 2" pipes instead of a single 3" pipe)>

I believe turbos need the exhaust evacuated quicker so it all 'dumps' into one big tube, pushed along by the turbo-ed gas behind it. I'm not 'up' on turbos but scavenging isn't an issue ?