Hi All - new member here.  For years I have considered building a Hi-MAX 1700 and looking to finally pull the trigger.  I am around a 215 lb pilot at this point though, which seems like the upper end of the weight range for this plane.  However, I am considering an engine with more power, such as a Hirth 35.  I was curious as to if anyone out there has a Hi-MAX with a larger/more powerful engine than the 447 and if so is there any modifications I should look to make to accomodate this. Or, if anyone in the same weight range is flying the 447?  Thank you for any insights.  

I mounted a Rotax 503 DCDI on my HiMax, due mainly to our elevation of 4100'.  David Cooper recommended I do so.  Be aware that the mounting hole distances are different for the 447 and the 503, so you will need to make a little room in the engine bay if you put electric start on it.  I went with an M5 starter and love it.  The Rotax manuals will give you the mounting distances so you can compare them.  Regarding pilot weight someone else will need to respond to that one.  If you look at the weight range charts in the POH you wont fit in the smaller limits, but I think you can in the larger limits (normal use).