What all is involved?

Which type of Abu?

I supertune all my Abu sweeden reels.
I use:
Abec 7 spool bearings.
Cog wheel with a bearing.
Worm gear with dual bearings.
Carbon drag washers.
All these parts cost 50-60 bucks depending who u buy them from.
It's super easy to install these parts or you can send them to a reel repair shop to install. I have no idea what they charge because I work on all my own stuff.

Any abu parts u take out make sure u keep because if you ever want to resell the reel you can put the old parts back in so u can reuse them in another reel. Same thing with a broken abu reel. The parts are golden.
I buy abu parts and broken abu sweeden reels also. Depending on the model I have paid $100 plus for a broken ambassadeur reel.

I had one a 5000 done some years back by Turbo Fred before he quit working on them, it is smooth as glass but still not close to my Lews BB1 Pro, BUT I still fish this ABU all the time and like it. Removing the level wind really will aid to casting as this was done a lot by those who were into distance casting.

I have a 2001 6501c3.

I guess you then have to guide the string with your finger as you reel?

I guess you then have to guide the string with your finger as you reel?[/quote]

Yes you'd have to guide it with your fingers.
If you upgrade the bearings and convert your reel to a ct without the levelwind you can easily cast out the entire spools line on a 6500 series.
Even with the levelwind I can cast out my entire spool on many reels. It just depends on the rod your using and the weight on your rig. I use 25-30 pound mono on most of my Abu 6500 distance casting reels.

I have a 4600 that we built from parts all mis matched colors that will empty the spool very easy with the level wind, we used German made needle bearings, light weight level wind shaft, carbon fiber pawl, shaft with bearings on both ends. I have had to replace 2 pawls.

Spooling an abu is very impressive! I'm going to look up some parts.

I just watched a few youtube videos. Looks like there is a ton of potential in these reels.

I've owned and sold a lot of the older round reels over the years. I'm not sure why I like them so much for bass fishing, but I do! One of the simplest ways to improve casting distance without making any changes to the stock parts is swapping out the brake blocks. Put in some of the blue ones and see how that improves the reel.

I will try new break blocks too. Thanks!

I have removed the break pads from all of my abu. reels. Have no problem casting without pads.

I played around with a lot of dual bearing and cog supported bearings, and my favorite economic setup was a single bearing levelwind with a bearing supported cog.

I found the cog bearing really helpful, but the dual bearing didn't add much over a single bearing levelwind assuming the cog was supported.

Throwing a bearing supported cog into a used C4 with carbon washers is my favorite way to have a supertuned ABU on the cheap.