What RC needs to do is bolt a backseat into a GT3. What is that, a one hour job?  But seriously. Do it. I know it's certainly going to be highly illegal  in an imaginary German way  

Porsche is basically calling bullshit saying that if you want a backseat you don't need something as sporty as a GT3. And if you think about it a high speed crash for a 911 backseat passenger would be horrific regardless of who installed the backseat. 

The fact is all engines should be gt3 engines in various tunes and displacement. Spend some money where it matters. Making them all the same is bound to save some money. In the air cooled days this was the case and everyone got a dry sump Mezger motor that could race on any track.  Engines could be rebuild and modified. Now they are now even visible. Ashamed is my guess.