I rebuilt my own C6 but I am far from an expert on the subject but I had similar questions when ordering my kit. When looking around on e-bay, there are a wide variety of kits available, some with all the parts, and some with only some of the parts. For me, I wanted to make sure to replace the filter, all the steels and frictions, as well as all the seals and bushings... Pretty much a complete rebuild. The servo will need to be ordered separately and should match the servo cover (or order yourself an aftermarket servo somewhere else for more holding power).

Something you might consider (which I did on my transmission) is to replace the pressure plate in the forward and low/reverse drums with a pressure plate modified to add an extra steel and friction. This was a factory option on several models of the C6 (not some aftermarket hack) and will give you more holding power in the clutch packs (less slipping, less heat, longer life, etc). Don't worry about the kit because it should already contain these extra steels and frictions as they have been made generic for all models of C6. Here's a link showing the pressure plate:
C6 Direct Clutch Stepped Pressure Plate - Broader Performance
Low/Rev Clutch Stepped Pressure Plate - Broader Performance

Another thing you might consider is changing the servo and lever. Following the information on this other forum, the firmness of the shifts between gears can be increased by changing the servo and lever. Harder shifts means less slipping, less heat, and longer life.
https://www.7173mustangs.com/thread-...vos-and-levers

You'll want to install an aftermarket "shift kit" as it will contain instructions to drill a certain hole in the valve body to improve lubrication in the transmission as well as replacement springs and things to improve the transmission operation.

Another thing that people do to improve the power capability of the C6 transmission is to get a hardened sun shell. This shell has notches around it which mesh with the cogs of the direct drum. If you put too much power to the front of the tranny, the metal of the shell can bend and ruin your transmission.

Another thing that people do to improve the power handling of the C6 is changing out the planetaries and increasing the number of gear cogs in them from 3 up to 5. Couple this with a hardened ring gear and it just keeps getting stronger.

If you want to free up a few horses, replacing the thrust washers with needle bearings will allow the parts to spin more freely.

Eh, that's all I can think of for now. I hope others add to the list.

 

 

Im in the same boat with you. My C6 has hardened seals and engaging slowly. Ive been looking at rebuild kits, shift kits, theres so much i almost want to pull it and just swap in a monster built c6 and be done with it.

 

 

I'm skeptical of the online stores and that stuff is waaaay overpriced. I've looked at their kits, boxed transmissions, watched their videos about "what they do"... It's all the same things as mentioned above including a vat bath and paint job. You're paying for the branding, imho.