Doing a slipon or exhaust change without an intake mod, the ecm will compensate and it will protect you from damaging the engine. It will not be properly tuned to get the right power out of the exhaust change though. Se there is a difference between "no problems" and " it runs like a raped ape now". The difference will be in the tune. If you or the op want to try to save money by not getting a good tune on your bike, go ahead. You probably won't damage anything. The guys that do spend the money are gonna spank you in HP and torque gains cause they tuned the bike to the changes made. Why the heck would one want to add exhaust to do nothing more than have the bike run the same or possibly worse than stock. What's the point. You all just trying to impress others with a loud exhaust. The OP is changing the way the bike will run by changing exhaust. The tables are not set for the new exhaust. There are many factors that will come into play, it is not as simple as if one does not change the intake, the exhaust won't have an effect on the amount of air through the engine. It will. If an intake can flow 180cfm and due to exhaust restriction is only able to flow 130cfm, Once the restriction is taken away, guess what, more air flows. Not to mention the way the air flows through the exhaust and scavenging effects, reversion, etc. There is a ton of info out there to educate you on this. There are lot's of posts out there on how much one has gained by getting the bike tuned. There is plenty of info on the utilization of exhaust types for performance gain after being properly tuned to the bike. The idea of tuning the bike is not some kind of ploy to get your money, it is the best way to extract what you can out of the modification made to the bike. Coldcase put up a great post... much more to it than just air in-air out. Also, an H-D master tech is not the one you want performance advice from. A proven performance expert is. When one need an operation, one does not seek out a general practitioner, he seeks a surgeon to do the job.

 

Also, an H-D master tech is not the one you want performance advice from. A proven performance expert is. When one need an operation, one does not seek out a general practitioner, he seeks a surgeon to do the job.


As I said in my earlier post. This HD master tech is also working on the side for an indy. Actually I think his latest project is a big bad 131 custom engine for a RK. So please.....just because he is an HD master does not mean he toes some corporate line. Far from it. Or that the extent of his knowledge comes from a book. If this guy was a brain surgeon and I had a tumor he would be my choice But he is the best I have ever met. So if he says it....I believe him. He has'nt steered me wrong yet.

The OP is going to do whatever he wants. If he wants top performance he will complete his S1 with a PC or race tuner and be done with it. If all he wants is a cool sound...good for him. Nothing wrong with that. I did'nt comment on this thread to get in a pissing match.

 

This is somthing that no one has ever been able to exlain to me. An engine is just an air pump...Suck, Bang, Blow. So, if no more air is "sucked" into the comustion chamber via a freer flowing AC..how does putting on a set of freer flowing pipes alone produce a leaner mixture if the "bang"(combustion) has already taken place at the point of the blow (exhaust)?

 

I was actually relating that to ghost riders quote about trusting any master tech in general, it was not really related to your particular mechanic. I think we all know the horror stories about the techs. one often encounters at the dealership. Obviously skills of technicians in areas of performance will vary greatly and in general a H-D tech is not nearly as trustworthy and knowledgable as one who builds race motors and makes a living off high performance applications for Harleys.
One thing about your post though, the OP is installing a full exhaust system on his bike. He is not installing slipons. He IS messing with the airflow. You asked your tech about slipons. Not a full system(and a short open system at that). Think about this, on his builds, if the customer were to change or try different exhaust systems, would he tune the bike for the different system? Of course he would. So if he is tuning different exhausts, wouldn't a stock bike need a retune as well? Again the answer is yes.

 

the A/C is not flowing air through the intake at it's maximum capacity. the stage1 air cleaner only actually help with flow and increases HP at around peak output in the rpm range(provide it is not restricted from the exhaust). Remember the air also flows out. different exhausts will allow more air to flow at given rpm ranges than others. Scavenging effects of exhaust, reversion and other factors such as length, width, bends etc. all change the output of the exhaust and affect the air that flows through at any given moment. When a exhaust restricts flow, less air is allowed to be sucked in from the intake cause it has no where to go. Blow air through a pipe. unrestricted, it flows at the rate you can blow. Now restrict it some and you can only get so much air through there. You yourself can blow more air, yet the air backs up and you can no longer blow as hard as you could.

 

I live it when Rounder chimes in... Solid knowledge.