I'm looking at swapping my V&H true duals for a Fatcat 2-1 on my 07 Ultra. I bought the bike used and it already had the Stage 1 intake, true duals, cams and headwork done. Can I swap the pipes without retuning? It'll be time to freshen up the motor next year and will be gettin it tuned then, if that's ok to wait that long.
I understand that I'll be missing some ponies, but I'm not too concerned with that. The bike seems to run a little rich as it is now

 

Do yourself a favor and tune to the new pipe. At least get it on a dyno for a couple of pulls to check AFR; it will take about 30 minutes and if the AFR is close enough, it will cost you about $50 and you will know if a full tune is necessary. Most tuners will work with customers this way; if your tuner won't; find another one.

 

That's part of the problem. There are no trustworthy tuners in my area. Jamie at FuelMoto will be tuning the bike next year when I have him freshen the motor up

 

I went from TDs to a 2-into-1 and had the bike tuned by the same shop for both. The change was remarkable! Get it tuned, but if you plan visiting Jamie next year, wait until then before changing your pipes. Pay to have it tuned once, ride it as it is for now!