Hello, I have a 2003 Nissan Maxima and I want to buy a new exhaust, it has a quarter size hole in it. I need the inlet diameter, muffler length and I need to know if the inlet/outlet is, offset or center.

 

Get a tape messure... Get down on your hands and knees by the muffler. Messure one end to the other and you get your length.... Messure Accros and you get your width... Then look where the exhaust pipe comes into the muffler either side or centre (offest or centre) and then look at the tip and where it comes out the of the muffler side or centre. This is the "hard" part. Then take your tape messure and messure across the pipe and you'll get your diameter...

 

 

You can also go to your local parts store and ask for a muffler/tailpipe for an 03 maxima.

Changing just the muffler won't change much. The stock resonator by itself makes the exhaust quiet.

 

It will if the stock muffler has a hole in it, as stated by the OP.