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

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+ depending on the unit) 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-$350). A bit more complex to set up than the TFI, computer skills needed (if you do it yourself ) and a working knowledge of motors/ignition systems to do it correctly.They also work well and are widely used.

The SERT ($350-$450)...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.
hey, Mr. Data. I too have been asking that question and been searching around trying to find the best, and best for my needs. I have 2007 fxst with vance and hines big radius pipes with arlen ness big sucker stage on air cleaner. A local Harley mechanic told me to go with the cobra fi2000 fuel tuner so I did. the bike runs good but my gas mileage went do the tube...or out the exhaust and there is no way to lean up the closed loop system on this tuner. So far I've looked at PcIII, fuel pak, screaming eagle race tuner, tfi, and the twin tec. You are the first person I've found that's said or knows anything about the twin tec. To me it sounds like by far the best, but they also make the twin tuner and I thought that my better suit my realistic needs, and was wondering if you knew anything about the twin tuner and what your thoughts were on it. thanks, I've read a lot of you posts and advice on here so I think your probably the best one to ask.
If you were to go with the 02 eliminators that are part of some of the tuners, you gain control over the entire fuel delivery and can lean out certain areas as needed. If you weren't going to do radical mods to the engine, I like the TFI by Techlusion myself and run one on my RK with the 02 eliminators and it runs well. If you had intentions of building the engine up, then the twin tec may serve you better. I haven't used a twin tec so I couldn't give you any pointers on the unit.
I like to keep it simple as far as FI tuners are concerned.

I have seen many people buy the self tuners (ie Thunder max etc.) and others and spend many hours/days/and weeks tweaking the maps to get it just right and later on post with a question about pinging.

To me it's overkill and often want to ask if all the work and time spent netted any significant HP or TQ than the basic system does. I'm sure they squeeze out a HP or 2 more, but to me I like to ride and not spend my time tweaking and adjusting, just cleaning and polishing LOL. In stock form these newer bikes run hot and anything in the way of a tuner whether it be the basic or advanced units will richen things up and cool it down some. I just do care to spend $500-$1000 for a tuner and spend considerable time to get it to run right. I have noticed and followed posts on the T Max and it seems that after the installation, the person doesn't post much any longer about how great it is and how much better the bike runs. To me it almost seems like they fade away and realize they could have done it for much less with a different choice in tuners but that's JMHO here. It's a very subjective issue and what one person thinks is great, another may not like for various reasons.

I've used the cobra unit also and the same holds true here about the fuel mileage down the tubes. The tech support for the unit is very poor. That's why I lean towards the TFI.
I wasn't really thinking of using the twin tec ($849) I was looking at the new twin tuner ($189) made by twin tec. The web page has all their info on it. But I still haven't decided. for right now I unplugged my oxygen sensors from the cobra unit and hooked them back up stock. the bike seems to run fine oil tem doesn't seem to go over 200-210 on an 85 deg. day runs about 170-180 deg. when it's below 60 degrees outside and my mileage went back to aroun 40 mpr.

I haven't really got on it to see top speed or anything but it still feels like I got the power I had before....not like I'm racen'

anyway thanks I might look into the tfi, but if you hear anything good about the new twin tuner by twin tec let me know.

oh yeah.....what kind of mileage does the tfi give ya?
My 07 RK gets in the area of 40 MPG give or take with the TFI and eliminated 02 sensors depending on how I'm riding it once it loosened up with some miles.
The 96 engines like to use some gas over the 88 and 95 engines. I've seen guys state that they are getting upper 40's and 50 MPG on the 96 too.
First thing here that comes to mind is that they miss calculated their MPG or that they are running so lean that the engine will suffer eventually from lean mixtures. I would rather sacrifice a few MPG for a cooler proper running engine any day.

The digital twin tuner is similar in operation to the TFI unit which I prefer myself for ease of installation and it does a good job. This tuner states that it can be used with Power Commander maps which tells me it differs from the TFI in that it can alter the ECM map in some way. Never having used one of these units, I wonder how they can state that if it just deals with fuel enrichment unless it is misrepresented in that it can be used piggyback over a PC map but that wouldn't make sense to me without the PC in place.
I've installed quite a few of the TFI units and not had any problems with any.
Most of the major names all have the unit that mimics the TFI in different packaging, some even made by Techlusion, the makers of the TFI.