The Stinger was flown this past weekend at Goddard (Wichita KS).

It really scoots with a 9 x 8 APC prop on the stock Thunder Tiger Pro 40.

We later changed the muffler to a Performance Specialties tuned muffler on the same engine. The prop was changed to 9 x7. This combination was even faster and I suspect that more speed could be had with some different props.

FYI - This Thunder Tiger Pro 40 and Performance Specialties (or Jett) muffler could easily make a step-up engine without spending a lot of money.