Hi
A friend who campaigns a 312 RWHP 1303 sports sedan uses toe in on the rear, he feels it helps him bring it back if the tail gets out.
I think the cheapest and best upgrade that you can do to any IRS VW is to fit 23.5 rear torsion bars from a Type 3 wagon or 944.
I'm not keen on using coil overs on the rear because of the load put on the rear shock mount.
Steve
The 312 RWHP 1303, he did quicker times than the new Skyline on slicks
http://www.youtube.com/watch?v=fvcoV53Stns