Correct diffs make a huge difference to how the car handles.
It wasnt till about this time last year i was having problems with my car then running a Xray T2. I was talking to probably there best team driver over here in the UK about it. He looked at my car and said the set up was pretty much the same as his etc the rear diff would be causing the problem. To be honest i didnt even think it would matter to much if the diff had a bit of grit in it. Just to proove the point i had a new built up diff in my box i swapped it over he set the tension of it which was pretty much the same as what i had anyway and then did my next run. I couldnt belive the difference in the car it felt the best it had ever done ever since then the diffs in my cars get rebuilt etc very regular.
Also on this point im interested to hear why some of you have been running your diffs on the Medium - Loose side ? Is this just with foams or with rubber aswell ?