Today’s exhaust systems consist of a lot of expensive parts. There are one or more catalysts, an oxygen sensor, maybe even a 2-stage muffler. There’s piping that’s not only shaped to clear underbody lines, but also may be made of premium metals, in some cases dual-wall tubing. There are sheetmetal underbody heat shields to prevent the exhaust from igniting dry grass.
More about exhaust systems at …… https://www.popularmechanics.com/cars/how-to/a103/1272466/
MG ZT info mods and maintenance 