No, it wont blow apart if you take it to 20K a few times.The bearings may go first after a while. There's just no power up there, so why go there. You want speed out of it, just put more pitch on a prop and make use of power at lower rpm.
After market tuned mufflers work great on it. You didn't mention what plane it's going on, that can help us narrow the prop pick for you.
More info here, read through it all as the performance search evolves :
http://www.rcuniverse.com/forum/m_5043356/tm.htm