Do you honestly believe that a full on WRC car with Active diffs, proper wrc front and rear end is not more effective than a well modified standard based cossie setup. Now I don't claim to know a fraction of Martins set up but I do know he hasn't got active diffs, and the rear beam looks to be based on the standard layout.

Put the same engine in both cars and which do you think would be quicker around a track? If it isn't why to the rally teams spend all that money on development