New shocks and super pro bushes transformed the handling on my car.
I replaced the suspension parts all round on my 2.8 last year including poly bushes in the wishbones, made a difference, but what made the most difference was new tyres, fitted Michelin Pilots sports all round. Totally stopped the tram-lining and the handling was transformed., however as a comparison just changed from Pirelli P6000 to Continentals on the ///M and the handling is worse. So I do believe tyres make a huge difference especially on the tram-lining and under-steer. (just my opinion though)My front tyres were mismatched too and had varying tread depth which is sacrilege on any type of roadster!
Think i read somewhere on this forum that certain brands of tyre offer less tramlining than others but can't find the thread.