Looking for opinions, I have a ttr90 with a Takagawa hyper S kit. Currently running a FMF core 4 ( it came on the bike). On ebay there are two pipes for sale with good prices. One is a Big Gun Evo Mini the other is a White Brothers R4 mini. Will either give me better performance or an I just waisting my money. Is there much difference between the performance of the three pipes?