I have recently brought a 2009 WRX s  hatch, the car is one owner 54k all standard as far as  i know ,when I drove the car initially it seemed 

to have a very quiet exhaust  considering its got a prodrive back box .when i had it up on the ramp this week i measured the exhaust bore size

from the cat to centre section its 2.5 inch dia  ,The centre section and muffler pipe is only 2.25 inch dia before joining the tailbox section which 

then goes back to 2.5 inch dia - the centre section has subaru stamped on it so its genuine is this normal for this model.?

is there a a way of deleting the centre box with a straight through pipe to match   

cheers in advance 

does anyone else own this model that's come across this issue ? 

Sounds normal on them mate. Only straight pipe sections I know of are aftermarket or custom piping. Prodrive exhaust on them is rather quiet really. If you want more noise either change the downpipe, or catback system. 👍🏻

Thanks