Wow! Lots of reading on this subject. I have an 07 FSXTSSE, Sceaming Eagle Softtail Springer.I have installed V&H Big Shot Staggerd pipes and a high flow K&N filter. I have the Screaming Eagle race tuner. So do I downlaod a stock program that matches my mods then take it to a good dyno and have it fine tuned? Looking at the stock programs I think #74 is the one. Does this stock program just get you close? If I do nothing to the ECM will it adjust to the mods I have done or will it go lean? What's the differance between Sert, PCIII or ECM downloads?

 

If you already have the SERT, you can load a map that's close to the setup that you have and get it to a tuner that works with the SERT. The nice thing about that is once it's dyno tuned the O2 sensors will make adjustments after that to keep it tuned. The SERT is a factory style tuning device, the PC3 is an addon that changes theECM signals but I've never seen them for use in closed loop EFI you have to eliminate the O2 sensors, The ECM download is a factory non adjustable ECM programing change that will help when you make air filter and exhaust changes. Hope this helps

 

ECM downloads are used primarily when a less restrictive air cleaner is used like your K&N.They keep the bike from running too lean but is still EPA compliant (keeps A/F ratio around 14.6). The bike will still run hot with a Stage 1 download - I know, I did it.If you have a late enough SERT CD, you have CLB (closed loop bias) tables for the various base maps which can be set to 798 for all table entries. This improves the A/F ratio to around 14.1. I have an '08 Ultra which uses a different base map than your setup. Hopefully one of the other guys can recommend the best base map for you to start with. Since you already have the SERT, use it vs. the PCIII. The PCIII just overrides the stock ECM settings and requires eliminating the oxygen sensors on your bike. The SERT gives you more tuning options than a PCIII. Finally, get a good dyno tune using your SERT to max out the performance potenial. If you max out the CLB table entries to 798 in the proper base map on your SERT, however, you will get good performance without a dyno tune. Lots of people have done this with good results (me included).