Powerflow is about customer choice and what you choose to have fitted is entirely up to you. It can be the whole system from the cat back, just the rear section or just the middle section. Either you can specify exactly what you want in terms of bore and silencer size, or you can tell the build centre how you want the system to look (ie choose the style and location of the tailpipe/s) and sound* and leave the spec up to them.  

 

Some build centres will also undertake work on the front pipe area of the exhaust, make up cat bypass pipes, replace faulty catalytic converters, fit high-flow cats, etc. 

 

*Please note that sound/noise is a subjective thing and while they will try to get as close as possible to what you want, they can’t always guarantee to make the system sound exactly the way you imagined it would.