About watt's links. We were told they were the holy grail. but here is our history and thoughts.
In the GA/IMSA CTSC, you had to use the Ford Racing rear lower arms with poly bushings and a panhard rod, we made the car work pretty good there. We bailed on CTSC and started looking at PWC for 2015. In the middle of the switch we rebuilt a car with the PWC stuff, and wing and splitter, spherical rear arms, took it to Laguna for the SCCA runoffs as a back up car, had to use it, and it worked pretty well even with our base "GS" setup.
For PWC we were told you had to have the Watts link to be competitive. So we purchased a car that was for sale that had been strong in GTS, looked at the watts link, did some reading, went testing and ran it back to back with our car at a track that we had never run our car on. Out of the box our car was faster. Our car only got better during the day, while the car with the watts link didn't show much potential after some tinkering. Went home found the diff cover was leaking and bolts had already loosened up and decided along with lack of speed it wasn't worth the aggravation. By the end of the season we were the highest finishing Mustang at 10 of 17 races, and in 5 of the races we were not, we finished directly behind the highest.
Now in both PWC and IMSA, you were limited to stock pickup points, PWC allowed the watts link, but no moving of pickup points. For something that is unlimited, you might find something, but that is going to be a lot of work and money. If you like to tinker, go ahead. In what we do with the rule sets we race to you have to keep the basic suspension layout and its kind of cool making the S197 fly as fast as we did while still sharing most pieces and design with the street car.
Is our setup for everyone one? No. Its pretty costly, and requires all the pieces of the puzzle to be put in place to make it work to its best potential. However I would feel fine selling it, setting it up, and saying go learn to drive it and don't over think as long as all those pieces were installed. I feel what is most frustrating is having someone bring their car in complaining of leaks, squeaks, and not handling right, all because they put *insert part here* on thinking just IT would magically change the car. But a lot people just buy random parts thinking it will solve all problems without proper setup or interaction with other parts. I feel so confident in what we use because it was fine tuned against the stop watch and took the checkered flag ahead of competition.
On messing with the rear end of the S197. If it could have been improved so easily, why did the car last until 2014, and why did it take so long to bring out an IRS car? Think about that.