If you’re working with a stock setup then you can probably find a downpipe for sale somewhere to bolt up for your swap. But if you’re working with a more custom setup then the downpipe is going to have to be custom fabricated to ensure a proper fit with your exhaust. The reason is because you’re going to want a custom exhaust manifold for the turbo application, and if you’re like me you’ll probably end up with a top mount turbo exhaust manifold.
There are a few things to keep in mind when selecting a turbo manifold:
- Never buy a generic EBay Manifold. You are asking for trouble. These are cheaply made, probably won’t support the weight of your turbo, and have a higher chance of cracking. Why take the risk of damaging your new swap?
- When planning for the manifold, be sure to take into consideration the downpipe placement with your steering column. There is not a lot of room for the downpipe or an external wastegate, but it can definitely be done.
- Not all manifolds will allow for the AC Compressor to be installed. If you want to keep your AC then you will need to make sure the exhaust manifold is built for that purpose.
You can spend a lot of money on manifolds, but the result can be worth it. Besides reliability, proper manifold design will allow for the maximum efficiency in airflow to your turbo. This means quicker spool and more power. Without going into a ton of detail, the main difference between a tubular, equal length manifold and a factory cast iron manifold is that you’re allowing the cylinder exhaust of each port to work in harmony to power the turbo. Otherwise you’re shoving air through the same area from different sources and those sources can fight each other, robbing you of power.
Here is an example of an Ebay manifold vs. two quality manifolds: