Thanks for the help Jon.
My father had a 1977 Cessna 340A on a 135 certificate back in the 90's, which being an A&P and working on it was my job. I wanted to change the Carenado 340A to the this one with the 310hp engines, so is the critical altitude around 20,000? We did have the vortex generators for the gross weight increase....but no RAM STC unfortunately.
I'm not sure, but I've heard 20,000 might be close.
Also, have you ever had problems with flying in heavy snow and moderate ice and engines loosing power like in the sim. I can get the engines to nearly quit in heavy snow and moderate icing.
Thanks John Wolfe