These FTSE 100 (INDEXFTSE:UKX) stocks could provide a powerful boost to your pension. : The secret to successful long-term investing is finding good companies that can deliver sustained growth. Although low-growth companies might beat the market over short periods, over long periods they probably won’t. Today I’m looking at two FTSE 100 stocks with an impressive track record of growth and a history of outperforming the market. Paper-based packaging specialist Smurfit Kappa Group (LSE: SKG) has been the subject of a takeover attempt by US rival International Paper for the last three months.