I thought if a pipe is too restrictive it could cause it to overheat or burn the piston up on the exhaust side?

It can if you're running the bike hard on long WFO runs and it depends on the restriction, porting, jetting, rider, conditions, etc.....A motor does not blow up on it's own it has to be ridden.

Your statements are not a complete synopsis of the entire situation and either you're failing to understand that they all work together to create a situation or your just looking to argue.

As you said your FMF works good for you for what you like to do.  I personally think FMFs suck and prefer a higher performance pipe especially for the money.  Does it mean just because you have a FMF on a bike you'll blow it up? Nope, you have to ride it, you have to jet it, it is subject to the riding conditions, the riders common sense (or lack there of), and the tuning ability of the rider or mechanic.

I don't know how much you know about 2 strokes but before there where expansion chambers you ran a straight pipe that you kept cutting off until you felt it worked good.

This thread was a request for a "good" pipe so if you need more education on how pipes work or what makes a piston sieze, please read some of the tech articles or make another post in the technical section but quit taking this thread off topic.

thanks