more powerful engine in fourtrak

Forum: 

Hi guys (and gals). I want to put a significantly more powerful diesel engine in a fourtrak for a project I am working on. Anyone got any ideas as to what more powerful engine would fit into the fourtrak with the least amount of modification? Ideally looking for an engine that is also tune-able. Get y thinking caps on. Would love to hear some tried and tested ideas as well as a few ideas thinking outside the box. Thanks.

why not tune the fourtrak

why not tune the fourtrak engine??
the only one i can think of that makes the trak feel slow and should be easyish to fit is the surf 3L engine