Ok is it&nbsp\\;true that you can replace the exaust only and the computer will adjust the fuel mixture or false? I heard if it is just for sound YES, sound and performance NO. Any replys please. Other words do you have to have new fuel mgnt. with new&nbsp\\;pipes?&nbsp\\;I have an '07 FatBoy. Thnaks, David.

 

no adjustment needed if you change pipes or breather if you do both you need help

 

+1 with Tinkermc

 

Sorry, but at least in the case of the current-generation EFI I got to disagree. Changing either end by itself will change the flow dynamics from stock. If you by chance change the dynamics linearly over the operating range of the engine you would be okay. But I do not see how that would be possible. Maybe 1 chance out of hundreds of tries. If the change in dynamics is non-linear then the auto-tuning will be wrong for the open-loop operation.

In their 07 catalog, H-D says their replacement mufflers, at least some of them for the touring lineup anyway, do not require remapping, but all of their intake parts, as I recall, did call for a remap of the ECU. What does that tell you? Maybe their EPA-certified mufflers effect a linear change in flow dynamics, or at least close enough, but the intake stuff alters them sufficiently to require attention.

If the mufflers flow more only at lower rpm ranges, then you will merely be richer than you need up higher. Same for the intake, but that is most unlikely as the butterfly itself is the limiting factor there.

If either flows better only at higher rpm ranges, the autotuning will not provide the necessary extra fuel there.

From an engineering standpoint, I would not do it for either case. From an experience standpoint, just touring Rush 2.0s cause weird artifacts open-loop.

 

Your experience?&nbsp\\;

 

Running just the Rush slip-ons with no engine management changes, for somewhat over 1000 miles. The tune moved around on me in ways I did not care for.

 

If you are concerned about it just go get the dealer stage1 download.