If you disconnect the Power Commander can't they still tell that you have been using a tuner? This is what has me concerned. I've read that you can use a aftermarket tuner and then when the time comes pull it and then just connect the SESPT as all they can see is that the ECM has had a tuner connected.
The PC5 is a "piggyback" tuner, meaning it does
not change the original fuel map. The piggyback tuners just
intercept the fuel signal from the stock map, then adjusts it up or down to provide more or less fuel to the engine. Piggyback tuners are hooked up to the bike and physically stay on the bike to work.
The "flash" tuners, such as TTS, PowerVision FP3, etc., actually
change the stock fuel map in the ECM. The word "flash" thus means "electronically changing /replacing" the original fuel map. After the new map is flashed into the ECM, the flash tuner is completely disconnected from the bike.
If you ever have to get warranty work on the bike, you remove the piggyback box from the bike before taking the bike in (to remove all evidence of a different tune). OTOH, with flash tuners, you have to hook-up the computer AND the tuner box to the bike, flash the original map back into the bike's ECM, then disconnect the 'puter and the box.
Here's where the posible '
rub' (no, not the rich urban biker, lol) comes in: b/c of H-D's lawsuit settlement with the EPA, HD gets to void the warranty if a non-EPA approved tune has ever been used in the bike. So HD put in an electronic "snitch' that tells them, when they hook-up their Digital Technician, that a different map has been flashed into the ECM...and if HD
doesn't have a note in their records that they installed an EPA-approved map...you are so $crewed.
Certain flash tuner companies claim their box eludes the snitch, and HD can't tell that your ECM ever had a different map. I have no experience with this, and as you can imagine, nobody want to be the tester for this. We make our choice, and take our chance. My choice was to keep the warranty by using the SEST to put in an EPA approved map. I'm sure it cost some performance, but with the sumping and fluid-transfer problems on the M8, that was my decision. Good luck with yours.