If you are working on ticking up your exhaust, an Invidia down pipe can be an important ingredient. It isn't a short cut so much as it is an efficient way to harness more performance that is restricted by the stock exhaust system. Serious drivers determined to gain more horsepower know that an Invidia down pipe is often the missing piece in a complete performance exhaust.
What an Invidia down pipe does is offer a one-piece setup that takes away the OEM catalytic converter. The catalytic converter is not normally removed being that it filters harmful exhaust gases and ushers them out through the exhaust. But this process causes airflow restriction that brings down performance. Using an Invidia down pipe instead frees up the exhaust flow much more liberally, which releases some extra horses. Invidia exhaust downpipes showcase a 4" bellmount that frees up the extra gas causing the restriction. This type of modification is most commonly employed by drivers who participate in racing competitions in a Scion tC or Subaru WRX.
There isn't one answer as to how much extra horsepower a racing downpipe is responsible for. Different dynamometer tests reveal different results. It depends on several factors, including if the racing downpipe is installed with other aftermarket automotive exhaust parts. Most drivers agree that the number is somewhere inside the 3-5 HP range with the Invidia exhaust downpipe.
Racing downpipes by Invidia can be installed with other auto exhaust parts or mated to the stock exhaust components. The flanges are CNC machined so that both the fit and install are not a headache. With other kinds of racing downpipes, sometimes the flanges are narrow. Narrow flanges can bend and are also eligible to crack. A crack in an automotive down pipe flange can lead to a crack that extends down the entire pipe. Invidia uses stainless steel not only for the exhaust downpipe, but also for the flanges for extra durability.
When you are searching for a turbo downpipe, it is a good idea to check your local emissions laws first. Performance car downpipes that replace your catalytic converter are often considered illegal and prohibit your car from passing inspection. That doesn't mean you cannot use one, however, they are intended for racing or off-road use only.