Have been using Powerflow for years when Sanjev was still in Edenvale , I honestly don't think his price is beatable.
When you look at his price and the quality of his work, it is not like you compromising on your system that is why I will go to Powerflow Randburg.
And most importantly his after sales service is great and your system will have a 5 year warranty if I am not mistaken, It is not the first time I praised Powerflow Randburg on the forum.
When I did my exhaust I dropped my car on a Wednesday afternoon, Thursday I was back because I needed the car for work, Even though I was told it will take two days, they worked extra hours, I think until 8 so I can get my car out.
About a month went by and somehow I was convinced that they used mild steel instead of stainless when I saw a picture they posted of a polished system. I called Sanjev and he asked me to bring the car in and if it is Mild steel he will redo my entire system for me. (He was on holiday when I sent my car in).
He put my car on the ramp to show me that it is actually stainless and showed me the difference, even measured the pipes for me. The reason I was convinced was due to them using a lot of Aerosault on the bends that made it look mild.
So I am not saying Powerflow is the best, but for the price and service, Its well worth it. Sanjev has been in the exhaust game for years. I suggest getting quotes from all the mentioned exhaust shops and see what best suits your pocket.