Thank you Jerry for the technical interpretation of my idiotic ramblings.

your original post said don't run fmf do I assumed bc your a forum moderator you knew what you were talking about.  so if pipes could have to much  restriction it could cause failure and was wondering if that was why you said not to run them.  I wasn't starting anything just wanting to know why not to run them is all

To answer your question, yes an over restrictive pipe can help cause you to seize a piston usually through the build up of too much heat as Jerry explained.

Pipes that have been known to do this are the Paul turner but only when ran on a bike with, porting, larger pistons, in hot conditions, run it on the lean side, with maybe non-race gas, in hot conditions, under hard loads for extended periods.  From what I have come to know the cause for this is not the expansion chamber but the diameter of the stinger section being too small and holding too much heat in the cylinder through exhaust gas restriction. 

Having said that Paul turner pipes on stock motors or with light porting run good and unless you're really running them hard for long pulls, have lots of porting (forcing lots of air through the motor), running them lean, or run low octane gas shouldn't have to worry about seizing a piston running a PT.  My riding buddy has had one for 3 years and it runs great, but it's on a stock motor, bigger carb, dry large intake, V-2 reeds, rides the desert with no issues.

Now I will also say that the Q pipe is notorious for holding heat in the head pipe due to the sonic transducer in the back of the convergent cone (rumor, I have not seen it myself).  From my real world experience running both Q V-1 & HPR the Q pipe gets hot and holds the heat in the head pipe creating a need for a break while riding the dunes or only allowing 3 passes on the hill before it gets too hot and the power would drop off (AKA risking seizing a piston from over heating (1,200+ degrees).  Riding the HPR with the larger diameter stinger and non restricted I can ride that thing for a hour straight and the only thing I need to cool it down is run it down hill, up shift, and under a light load so the motor can pull a fresh charge in and cool the motor and head pipe down, then I can hit it again. 

I can definitely feel the difference in how much heat the Q V-1 hold VS. the HPR which dissipates the heat very quickly.