I took off my stock pipes and put on some Harley performance pipes that I had on my 02 Road King, that have since been discontinued by Harley. Great sound and no discernable difference in performance. Occasional very light pop on decel but not always. I have not done anything with the air filter at the moment it is still stock.

Any reason to recalibrate the ecm?

 

I have a friend with a 99 Ground Pounder with a 113 S&S, he put on hooker header straight pipes and hashad no problems. He said he even got a better result at the emissions testing (Yes in Arizona they test bikes too!) The only way to be sure is to run a dyno before and after the pipe change. Presuming you have a Munki or S&S carb you can allways by a variable enricher valve and tune it to what you think is best.

 

Whoops sorry, I thought I saw you had a "Ultra Cycle" that why I refrenced my friend. I think the dyno is the only way to tell for sure, I would just go with "your gut feel" if I was you.