I too have a 2003 Fatboy and I had the dealer install one of the EZ pull clutches. It's Ok, I did notice a little easier pull but not much. I only did it so my girlfriend could ride the Fatboy. The clutch was difficult for her before.

 

Mueller power clutch. Works nice.

 

Just installed the Muller Power Clutch. Adjusted per their instructions it works like a charm and just as advertised. A little pricey, but very well made and I am completely satisfied. It made a dramatic improvement in clutch lever effort on my '97 Sportster. Wish I had added it years ago.

 

I don't understand why it won't lock up just as before. You are not changing or modifying the spring pressure at the clutch basket. Shouldn't be any different if it's a modded topend or not. Also, not aware of the Baker transmission itself being different with regards to clutch works. (Other than superior materials and workmanship.)

I'll give you proper adjustment is critical as you're only moving the actuation rod about 60% of stock travel. But, once it's adjusted, it certainly is a nicer, better feeling, wider friction zone clutch.
And yes, the pic I posted above is from my personal bike (2016 FXDL).

 

My 1990 FLHS came stock with a different ramp angle making the pull easier. It did reduce the amount of throw and it wore out throw out bearings if it wasn't adjusted just perfectly. I removed it and couldn't feel any difference.

 

I've checked out the Burly Easy-boy Lite clutch, also the E-Z Pull Clutch assist and both sound similar with basically the same type reviews. Then today I found the Harley Davidson Easy Pull kit ,,

https://www.harley-davidson.com/store/-n-a#tabs

and now I'm wondering if anyone on the forum has had experience with this unit ? Pro/con

 

Says it comes "stock" on 2007-later big twins. Guess I already had it on my 2016. Now, it's even better than that with the EZ Boy Burley. I have no arthritis now, but everyone says that, until they do. Why wait on such a simple fix that works so well. (It's cheap too!)

 

Clutch Wiz, 10 minute install by any amateur. Reduced effort on my '16 by a good 35%. If you are heavy handed, you may need the Screaming Eagle heavier pressure plate, but I didn't on a Heritage. Think it depends on weight of bike. It is so easy to install and machined so well, you need to take a look. It was originally designed for Tri-Glides because of their heavy pressure plates.

 

Do you recall how long it took to install it ? Currently my bike is at the local Harley dealer service dept getting the Burley Easy Boy Lite clutch kit installed, along with a 5 point adjustable clutch lever. I'm curious as to how long the shop time will be just for the Burley kit. If you say it took you an hour and they charge me for 3, then I'll be doing a dance on the service counter

 

It's a 20 minute job. And that's if you're very careful and unfamiliar with wrenching.
The only thing that takes time is rethreading the clutch cable into the case threads. Sometimes, cleaning the threads with a tap helps start the cable shroud into the threaded case.