Just received FMF-Power Core 4 for my 2008 DR650 and seems like I need adapter piece or something? OD of original slip-on is 38mm, OD of FMF is 42mm. In addition from the front bolt on connection of the FMF to end of pipe is about 30mm shorter than stock. I did the search deal on this site and in pic. of FMF compared to stock you can see the difference. What am I missing here? Thanks for responses.