@jfri "more powerful plane" is a bit vague. Specifically, it's an arrow fitted with a turbocharger, which does make more powerful, though the effect is noticed most at higher altitudes. Basically, the turbo variant can go higher before efficiency diminishes due to less dense air, which means you can go faster and cruise up to FL200.
There are a few other differences, such as the interior color (non-turbo iii is red, turbo iii is blue, and turbo iv is beige I think). The turbo variants also only come with a clean interior, while the non-turbo gives you the choice between the clean and weathered interiors.
The flight models are constantly being improved, and I would say currently the non-turbo and turbo arrow iii's handle adverse yaw quite differently. Never having flown a plane, I don't know which is more realistic, but the good news is they are always making improvements based on the real planes and community feedback.
I have not noticed a performance hit vs default planes, and I believe that is something that JF specifically had in mind when designing the planes. The textures in some areas are lower quality, but it's mostly places you won't be seeing 99% of the time anyway (e.g. the ceiling). And with little to no glass screens, there isn't much else to suck up FPS.
Hope this is helpful!
