Many have asked the same question of which one is best for me...

Here's a listing of the discounting dealers... HERE

Your choice as to which one to use should based on a few things...

Your budget should come first, your skills for setting it up if you are doing it, your plans for future modifications and how far you wish to go with the tuning.

The TFI ($160) would be the entry level with no major mods such as heads and radical cams planned in the future. Easy install and setup, can be done by most DIY'ers with minimal tools and knowledge, lowest of the prices. Very good results too. Very widely used and results with the intake and exhaust coupled with the TFI will be in the 8-10 HP range. Not much more gotten with other more expensive systems here.

Next comes the HD race fueler ($180-$200), similar to the TFI but with 2 additional pots to tweak for crossover. No real benefit to them IMO

Next I would say the PCIII ($250-$300). A bit more complex to set up than the TFI, computer skills needed (if you do it) and a working knowledge of motors/ignition systems to do it correctly.They also work well and are widely used.

The SERT ($350-$400)...probably one of the best ways to go, but again complex to set up and the above criteria holds true here also.(skills etc.)

Then there is the Twin tech with 02 sensors($700 range+), similar to the S&S IST unit that will tune as you ride, again initial set up as above with skills involved.

Pretty much all but the TFI would benefit more with dyno tuning and professional install and setup if you are not familiar with the systems otherwise you can hurt yourself more than you can help yourself, end up with problems with pinging and poor performance and possible damage to the engine as a final result. They offer canned maps for most units except the TFI that will get you close, but from there you can tweek it even more for better performance.

If you don't think you are capable of programming the systems, by all means have it done by a professional. JMHO