Here is something I've recently learned...I thought it was pretty interesting...Maybe some of the experts can confirm...Or feel free to correct me if they dis-agree...

How "sensitive" is your needle valve adjustment?? In other words...do you go from rich to lean in just a click or two?? Or do you have something like a half of a turn between rich and lean???

If the needle is "hyper-sensitive"...You may be on the short side of tolerance on your pipe...Albeit...You are tuned for Maximum Performance...But your on the edge...

I've personally decided to tune a little more conservative than the "Razors Edge" so to speak...I want to have about a half of a turn on my mixture adjustment...Then I'll "adjust" the engine slightly rich for flight...

If your in that hyper sensitive regime...You may add 1/2" to your pipe and see how you like it...Then you may want to cut it down to 1/4" if that is too much...

Just some food for thought...(You may already know this??)

Chuck