I was just looking at H-D p/n 64800043 Which is a new high flow exhaust with Street Cannon style mufflers.

I figured if it was any good, H-D would have a special tuning file for it. I can check online since I own an H-D Street Tuner. Yup, there is a new tuning file already posted.
I compared volumetric efficiency (VE) tables to what I am running now and there is a 9% gain from 3000 to 4000 rpm on a stage one engine. This is comparing a bike that is already stage one, to a stage one with the new exhaust system. That is quite an improvement as a 9% increase in VE will call for 9% more fuel and make 9% more power.
With 2 cat converters each getting 1/2 the flow they will each put out 4 times less heat intensity than the stocker and they are back behind the rider and passenger.
Here's a plot for the gain with a Stage II 255 Cam (nearly the same as our stock high output cam).


I figured if it was any good, H-D would have a special tuning file for it. I can check online since I own an H-D Street Tuner. Yup, there is a new tuning file already posted.
I compared volumetric efficiency (VE) tables to what I am running now and there is a 9% gain from 3000 to 4000 rpm on a stage one engine. This is comparing a bike that is already stage one, to a stage one with the new exhaust system. That is quite an improvement as a 9% increase in VE will call for 9% more fuel and make 9% more power.
With 2 cat converters each getting 1/2 the flow they will each put out 4 times less heat intensity than the stocker and they are back behind the rider and passenger.
Here's a plot for the gain with a Stage II 255 Cam (nearly the same as our stock high output cam).
