Originally Posted by Dave Wilshere

Cooler tailpipe temps with larger diameter...
The biggy is static thrust, most models (scale) are over powered for most people's throttle use! For a sports jet there is an optimum, for scale run as large as practical and its usually right.
142-180 motors can share a pipe, 90mm is my go to size, 92-95mm 180. 100mm 200 big block

Most people set the tailcone to tailpipe distance wrong and this affects thrust more!