RE: I need help with my OS GT 33 installing it into 27% EDGE 540
It's normal to have to cut a model airplane's cowling to accommodate the engine. No way to get around it. You just try to minimize the damage. Also, please realize that you may have to cut the cowl quite a bit to allow for proper cooling, depending upon the engine's actual performance once you start flying it.
We'll check what OS printed in their manual, and let them know of any discrepancies. Many engines don't come with a template at all...or even a chart with measurements. You have to measure the engine and go from there. Every installation is a custom job, so you wind up doing a lot of measuring, anyway.