I've got an 06 crf 450r and I put the EVO R system on my bike. The thing pulls hard down low and the mid but the top falls off. I changed the factory jetting (168) up to 175 and down to 162. I still had this prob. I can't tell if it's revving out or not. If it is, it seems you would have to short shift it. I like the factory pipe better. Can somebody offer suggestions to resolve this prob? Has anyone had this type of problem after adding an aftermarket exhaust? Please help !! I've contacted BG and they're about as much help as a hole in your head. All they say is "well it doesn't do that to our bikes". I took it to the dealer and the mechanics said I was revving out but it just seems to bog. This is my 1st thumper so it's a learning curve for me. Thanks in advance.