Refer to this in relation to taking the exhaust off.
http://www.renntech.org/forums/index.php?showtopic=7325&hl=exhaust
its easy to remove apart from the 2 bolts on top... these will test your
patience.
The sound is not much louder, but noticeable. The dead silence that was standard is gone.
If you want it louder drill il bigger. Quieter, drill a smaller hold. The hole i made was aout 1.5cm across.