Aren the stock manifolds and exhaust system restrictive?
For certain normally aspirated or supercharged systems, stock exhaust is somewhat restrictive and can cause backpressure in the system and rob HP. However, with turbocharged applications, the turbocharger is the biggest restriction in the exhaust system. All of the exhaust gasses (except the ones that are vented out the wastegate) pass through the turbine housing. The inlet hole in the turbine housing is about 2″x3″, however, as it scrolls around the housing it gets smaller and smaller causing the exhaust gasses to increase in velocity. At the smallest point where the gasses exit and hit the turbine wheel, the hole is no bigger than about 1″ in diameter. This tiny hole will create backpressure in the entire exhaust system prior to the turbo and clear back to the exhaust valves. So sticking larger diameter pipes and high flowing headers doesn’t make lots of sense when you have a 1″ tailpipe hole. These additions probably won’t hurt, but the money would be far better spent elsewhere. Our
