[mylesdw]

According to Herb Adams, it is very difficult to build anti-squat into an IRS where the diff is bolted directly to the chassis and none of the torque reaction is transmitted through the suspension. Some anti-squat can be gained by the positioning of the rear suspension members but the practical limit is 25% (compared with 100% for a well set up live axle). He says:

"Because independant rear suspension systems do not have as much anti-squat, they are not as good as a live axle in getting the power to the ground on high performance cars. This problem is not too bad with a rear engined car because of the rear weight bias. On front engined cars however, it is a distinct disadvantage"

It seems like the word is: there is not a lot you can do about squat in a powerful front engined car using an IRS. Better I guess to optimise the rear geometry to minimise camber change under those conditions.