TM have terrific detail and build quality, but unfortunately if you want to boost your velocity, these guns are designed for Japan's 1joule rating and plastic works just fine.
If you want to modify them for North American velocity allowances, then they will fall a part or wear out faster. Unless you have $$$ to upgrade most of the parts to do it.
Why not go with a maker like KJW, KWA or VFC which comes with all metal and higher velocity for our market place.
Does it makes sense to gut out 90% of the pistol, when there are others comes shipped all metal and higher velocities?