Monster S2R and S4R differences?

Funny that my friends are car enthusiast. They think that the radiator of S4R makes the bike looks even faster because the radiator looks like the intercooler from turbo cars. But one thing S2R better than S4R is when both changed to full exhaust system. The 2v motor always sounds better than the 4v. But when talking about horsepower, me (I have S4R) and my friend (he has S2R 1000) both agreen that the S4R is much more powerful than S2R 1000.