Increasing aircraft performance can be as easy as changing your exhaust system.  Performance gains are significant.  On a PA-12 customers have reported performance gains as follows:  @2400 RPM fuel consumption was 9.2GPH and with the LEES exhaust system it dropped to 8.3GPH and @2300 RPM it was only 7.8GPH. You have to keep in mind that this  is with an O360-180HP engine. We saw a static RPM increase of 75RPM and a 250'/per minute  increase in his rate of climb. With the stock exhaust we could never reach redline with the throttle full bore and  with  LEES' exhaust we are now getting 2800 RPM.

After the successful first flight of its sensational new D-JET on April 18th, Diamond continued with an aggressive flight test program with additional flights on April 19th, 20th and 21st to further expand the speed envelope and continue evaluation of handling characteristics.