If you’ve checked out our 5 best mods for the 3.5 EcoBoost guide, downpipes topped the list as one of the best mods for the F-150. Downpipes are the most restrictive component of the F150’s exhaust system which means upgrading to a less restrictive downpipe can have some significant performance and power benefits.
This guide will focus on the benefits of upgrading your downpipes, the difference between catless and high-flow catted downpipes, and the best downpipe brands for your F150. While this guide is more tailored towards the F150 specifically, it is applicable to all Ford’s with the 3.5 EcoBoost engine.
What is a Downpipe? Ford F150 EcoBoost
Since the idea of turbochargers is pretty new for Ford trucks, we’ll give a brief overview on what a downpipe is and why it’s a common modification for turbo engines.
A downpipe is a component of the exhaust system that bolts up from the turbocharger to the cat-back portion of the exhaust. Downpipes are unique to turbocharged engines but are in a way similar to headers on a naturally aspirated engine in the sense that they are the first component of the exhaust system.
In most turbo engines, as is with the 3.5 EcoBoost, the downpipe houses the primary catalytic converter. Because it bolts directly up to the turbo itself and houses the cat, it is the most important and most restrictive component of the exhaust system. Adding a catback exhaust to your F150 usually doesn’t add too much power because all of the restriction sits within the downpipe.
With the restriction being in the downpipe and the downpipe being attached to the turbo, it creates a lot of backpressure. This backpressure affects the turbine wheels ability to spool as the pressure creates restriction. You want the highest pressures pre-turbo and the lowest pressures post-turbo. Upgrading the downpipe is the best way to lower post-turbo pressure.
3.5 Ecoboost Downpipe Upgrade Benefits
- 10-25whp gains
- 10-25wtq gains
- Improved turbo spool and turbo efficiency
- Less backpressure
- Decreased EGT’s (exhaust gas temps)
- Slightly louder exhaust tone
The primary benefit of upgraded downpipes for your F150 is the reduction of backpressure in the exhaust system. Running no exhaust system after the turbo is actually the best exhaust for a turbo engine, however, this isn’t quite possible due to emissions. However, because the downpipes house the primary catalytic converters, they become the biggest creator of backpressure in the exhaust system.
Turbochargers spool more efficiently when there is a bigger pressure drop from pre- to post-turbo. Because the catalytic converter is restrictive it creates post-turbo pressure which reduces the turbochargers ability to spool. By reducing this backpressure there is less force against the turbo allowing to spool more easily and more quickly. And a more efficient turbo is a more powerful turbo which is where the majority of the power gains come from.
Gen I vs. Gen II 3.5 EcoBoost Power Differences
The Gen I 3.5 produces 365hp and 420lb-ft. of torque bone stock while the Gen II produces 375hp-450hp and 470-570lb-ft. of torque.
The primary difference creating the increased power levels is the addition of port injection alongside direct injection. Additionally, the turbine wheels are lighter and an electronic wastegate was added. While the performance benefits of upgraded downpipes are similar for both generations of the 3.5 EcoBoost, Gen II engines will see slightly more power gains due to the turbocharger upgrades.
F150 Catless vs. Catted Downpipes
The two options for upgraded downpipes are catless or high-flow catted downpipes. As the name insinuates, catless downpipes completely remove the catalytic converter. Because the catalytic converter is the most restrictive part of the exhaust system, opting for a catless option will reduce backpressure the most and provide slightly better power gains.
High-flow catted downpipes keep the catalytic converter but opt for a higher flowing cat that is still emissions legal. However, because they still have a cat they will provide less power gains to the tune of about 5-8whp compared to catless options. Although the tradeoff is keeping your car legal and being able to pass emissions testing.
While catted options provide less horsepower gains, the increased flow is still a huge improvement over the OEM downpipe. Given the recent emissions crackdowns, sticking with a catted option is the safe bet. We would only recommend the catless option for those who are trying to push serious power for track applications, usually with and upgraded turbocharger setup.
The only other worthy mention benefit of catless downpipes is the bang for the buck factor. Because they are a hollow pipe without a cat, they are about half the price of the high-flow catted options.
Biggest power gains + best bang for the buck = catless.
Emissions legal + still good power gains = high-flow catted.
Best 3.5 EcoBoost F150 Downpipes
Due to recent emissions activity with the EPA finding catless downpipes for sale online is becoming difficult. The best way to find some is to look on forums and marketplaces for used options.
Additionally, it is worth noting that EPA regulations vary by state to state. Catted downpipes are still considered illegal in some states such as California so please check what your state and local regulations are for downpipe upgrades. While most of the catalytic converters are EPA-approved, they can still be illegal in certain states.
Best Catted Bang for the Buck: SPD Performance F150 Downpipes
SPD Performance comes in as our favorite “bang-for-the-buck” downpipe at a cost of $795. With most catted downpipes running upwards of $1,300, this is a great option for those looking for a high-flow catted option.
With 3″ piping and high-flow EPA approved catalytic converters the SPD system offers a big improvement over the stock downpipe system.
Buy here: SPD 3.5 EcoBoost Catted Downpipes
Budget Breaker: AMS Performance F150 High-Flow Downpipe
AMS offers a top of the line downpipe option for the 3.5 EcoBoost F150. Coming in at $1,800 this is one the most expensive and premium options on the market, designed specifically for race and high power applications. With 3″ piping and a 25% increase in inlet surface area, the AMS downpipes offer the highest flow and most backpressure reduction in the market.
Buy here: AMS 3.5 EcoBoost Downpipe Upgrade
Catless Option: aFe Power F150 Downpipes
For those looking for a catless option, aFe Power manufactures a 3″ catless option. Coming in around $500 these downpipes will offer more flow and less backpressure compared to the catted options. However, these downpipes are aluminized steel and not stainless steel. This will cause these downpipes to wear down and rust more quickly in wet climates compared to stainless steel options.
The one setback to this downpipe is that it is catless making it illegal. Additionally, it is becoming more and more difficult to find them for sale online as most performance parts providers are backing away from selling catless products online.
It is worth noting that there are a lot more catless downpipe options available on eBay. If you go that route just make sure you verify the fitment of the piping before purchasing. Catless exhaust systems are pretty much just hollow pipes so opting for a cheaper eBay option isn’t going to hurt your engine.
Buy here: aFe Power Catless Downpipes
F150 3.5 EcoBoost Downpipe Summary
Upgrading the downpipe on your F150 EcoBoost 3.5 is hands down one of the best modifications. Especially when coupled with a tune and intake, higher flowing downpipes will provide exceptional performance benefits through increased turbo efficiency.
Catless options will be slightly louder and offer 5-8whp gains above high flow options. High flow catted options are legal in most states with the exception of CA and NY currently. Neither catless nor catted options will provide extremely loud exhaust notes. You should expect very modest sound improvements unless you opt for adding a full cat-back system with the downpipes.
Overall, downpipes are a worthwhile upgrade for those looking to add some additional power to their 3.5 EcoBoost F150’s.