The engine should be well broken in as it has way more than 6 tanks run through it. I am running a 13 x 8 APC prop, but I will try the 14-6 to see. With the original muffler, it has a low idle, so I think the low end is set okay. I know about only turning the low end very slightly and when adjusting and this is how I do it. Midrange doesn't concern me much and at full throttle it is fine. The transition from idle to full is also okay. I have one of the two exhaust tubes blocked off now with an automotive upholstery fastener and I need to see what that does. I have a Magnum .91 RFS NIB that I was saving for another project, but I would rather stick with the Super Tigre.