I stretched my Viper using all Yamaha parts and installed my Viper/SRX rear exchanger with only 1 small issue. I had to relocate the hole on the extension for the bleeder screw. Other than that it fit like a glove. Hope this help's ya out .
Snakebit, My tunnelextension came of a MSRX,so there may be a difference between it and a MM extension. And yes, my cooler is curved to fit tightly against the tunnel closeoff panel in the rear of the tunnel. I have'nt seen a MM cooler, so I don't know if they are the same or not. Sorry if I confused you, just trying to help a Yamabro out.
Yes, if it is an MPI you will need a flat cooler. The dimensions are different than the Yamaha extension. I used all secondhand parts to do mine and saved quite a bit of $$$. All my parts were purchased from members here. As far as your cooler goes, call Rich or MPI and they should have specific answers to your questions. Good luck.