I wouldn't be so quick to flame man...

Yes Higher than stock RPM causes the valvespring to compress and rebound in such a violent motion that the valvetrain assembly can lag behind the camshaft lobe and cause the piston to slam into the floating valve...

Yes, Higher Lift Cams at stock RPM Can Compress the Valvetrain and cause binding as when the coils of the spring bottom out and the piston can hit the valve if it doesn't have the clearance for it...This will also cause you to Drop a Valve, since the locks can and do fall right out, causing the valve to be dropped into the combustion chamber...

But, you have to realize that the High Pressure that is being Forced into the engine is pushing right into the back of the valves head and is resisting the valves return to the valve seat...This is why valvesprings are a neccessary upgrade on anything higher than, I will say, 12psi on a Boosted Honda motor...Now, 12psi on a T25 will produce a lesser volume of air than 12psi on t3/62-1, so maybe the resistance will not be so great that the stock valvesprings can't handle...

Using a Light Weight Flywheel is another reason to look into upgrading your valvetrain...Same with a lightened rotating assembly...The faster your engine will rev, the less time the valvetrain will have to compress and rebound...

And, as you know from driving boosted motors, once the turbo spools, the RPM rises very quickly due the volumetric effieciency of the motor reaching up and over 100%...This is another reason to upgrade the valvetrain...

If after reading these examples you feel I am wrong, please argue the point of the stock valvetrain not making a difference in a healthy boosted motor or any incorrect information in anything I have said...

This is all based on Engineering, Physics, and my Logic...Not 100% on my personal Experience...

Zee