There is no real evidence to prove that a concentrated portfolio performs better - whatever evidence there is, it would be only anecdotal. If you give the example of Rakesh Jhunjunwala (concentrated portfolio), I will give you Peter Lynch (diversified portfolio). If you put forward Rs. X, I will put forth Mr. Y.
Most MFs in India hold 50 plus stocks - it doesn't mean all of them fail to beat the index. Taurus MFs mostly have less than 10 stocks - but they are among the worst MFs you can buy in India.
So at the end of the day, your performance depends on the quality of stocks that you pick & host of other factors rather than the absolute number of scrips.
There is only one proven rule in investing - capital appreciation in a stock over a period of time depends on its earning growth. Now if I find 90 plus stocks at a decent valuation with both past history & future probability of earnings growth, I will buy them!