Nothing should be loose, Arkz, because something will break sooner or later.

You could easily try reducing the nitromethane percentage and reducing the glow plug heat range.

If your engine has high compression and improper cooling and/or lubrication, it may be suffering pre-ignition (an advanced ignition point).
That pre-ignition interferes with the proper functioning, making it look like the pressure is too much, when it is just the right pressure but happening too soon (before the piston reaches the top position).

Read this article:

http://www.flyrc.com/articles/tune_your_engine_1.html

Welcome to the forums!