Hi,
I will most likely go with the OS 55 and a Jett Stream muffler system.
I have already enquired about the Jett .56 and have read it is a great engine, the thing turning me away right now is having to cut the firewall etc to squeeze the bubbleless fuel tank into it...
I know the OS will be slower than the Jett, but I also don't want all the other hassles....

On a sidenote, I have heard Jett makes the tuned pipe for Evolution??? Is it the same as there Jett stream, will it fit an OS 55??