Early days yet but l have thoughts of changing out my diff for LSD unit with 3.27 ratio.
The problem is the TCU throwing a hissy fit when it checks the wheel speed verses input speed and finds they no longer align.
Does anybody know if there has been any solution found for this problem.
There were several solutions mentioned in my research but they were several years old and am curious as to whether or not others are now available.

 

There will also be a niggle with the TCM which monitors input-to-output shaft speed differential especially prior to kick-down. I don't know if this data comes from a Sensor within the Transmission or the wheel speed sensors? If the reference comes from the wheel speed, and you've changed the diff ratio for much faster acceleration, then there will be mid-range scenarios when kick-down will not be supported.
It's the same protection system that stops kick-down to 2nd gear at 100mph. When output shaft speed is too high verses input shaft speed (available engine rev range).

 

It is the TCM l need to address. The w5a580 box gets both input and output shaft speeds internally but that is primarily used for ratio selection. It gets car speed indirectly from the abs wheel sensors and the TCM will assume something is slipping if the numbers don't match up. Apparently reprogramming is possible. Mexico market cars were fitted with the lower ratio and TCM replacements are supplied unprogrammed so it can be done, just need to sort out who and how much.

 

I did the QUAIFE install along with the diff ratio 3.27:1 Mexican unit on a 4.0 XKR for a customer.

The TCM DID need to be reconfigured by a company before the car was driven.
The customer sent the TCM out for conversion while I did the QUAIFE and ratio work.
The engine was also fitted with a larger crankshaft pulley to spin the SC faster.
I installed the TCM in the car and went for a test drive. (WOW)

I never did a full throttle launch but I did 'put-my-foot' into the throttle a bit. It set me back in the seat!!!!!!!!!!!!!!

The customer gets to push the car to the limit and break it if that is what is to happen. I don't like to damage a car or drive it like it is mine.

A few months later the pinion shaft tooth broke and destroyed the 3.27:1 gear set. Found another diff in England from a 3.2 liter sedan to modify and install in the XKR.

I swapped propshaft flanges and cut the JURID flange extension on the sedan pinion shaft.
Reinstalled the QUAIFE and reset the crownwheel/pinion mesh/backlash.

I don't know if the car is still working after all these years??? It worked well when it left my shop.