I made a schedule checkup for the coming wednesday and I was told I had to replace the 'muffler' since it's rusty and I didn't change it last time. Now, I was wondering what the 'muffler' is in which they're going to replace, is it the whole cat-back system? or just the rear boxy 'muffler' part? Because what they call the 'muffler' is gonna cost me $480 CDN (about $300 USD). If it really is just the rear end part, I'd rather go aftermarket.