I fitted a 20 mm Whiteline front bar, and even on the softest setting it made the steering more positive with quicker turn in. It also gave the car a slightly firmer ride with
slight understeer but this was easy to live with.
But later on when the time came to fit new tyres, although I stuck with the stock 225/50R15 rear size I took the opportunity to fit wider 205/50R15’s on the front rather than the stock 195/55R15’s I had previously.
This, together with a bit more front castor made the car balance about nuetral
with even better turn in.
I believe that the stiffer bar was well worth fitting on the front, but I kept the stock bar on the rear.
The general consensus seems to be that going stiffer on the rear will contribute to more oversteer, something you may not want with your MR2.