Im curious to find out why the muffler is mounted on the LHS. As i was having a look under my car today the routing cuts through from the RHS at a 45 degree angle underneath to the LHS. Because for better performance you would want as straight routing as possible right? Then why not have the muffler on the RHS? Sorry if my wording has confused you.

I understand what you mean here tho. It's a common misconception that a straight thru exhaust builds the most power. In an NA car a straight thru exhaust of proper size will flow more power up top in the RPM range and allow for the maximum HP but will seriously cut your low end torque due to a drop in backflow - so it's a trade off really.
In a Turbo car the Turbo itself is all the backflow pressure your engine will ever need so large diamter and straight as possible for this application.