Yep, cheap thrills... in the Summer even solo you would be lucky to get a 150 to 10K, regardless the last few thousand feet take forever, and you sure won't get there in a spiral. Many turbocharged piston planes will go much higher than advertised. The reason they are not legally permitted to do so is they would be operating outside the parameters of the flight manual. One of the biggest reasons most of the aircraft with this capability are not certified to operate at the higher altitudes is that the certification is more involved and expensive. Nevertheless, many folks have taken Cessna Turbo 210's, for example, over 30K...