We're finally getting around to writing about upgraded N54 inlets and outlets. Oddly, they're mods we often overlook despite running upgraded inlets and outlets on our 2007 335i. Inlets and outlets are also some of the best mods for the N54. Turbo inlets are the intake pipes that run from the intakes to the turbos. Outlets run from the turbos to the intercooler. The OEM parts are highly restrictive and greatly limit airflow. In this guide, we'll discuss upgraded inlets and outlets and provide a few quality options on the market.
Why Upgrade Inlets & Outlets?
We won't spend much time on this, but wanted to provide some quick information. As stated, the OEM turbo inlets and outlets are highly restrictive on modded N54's. They were clearly not designed to efficiently support higher than stock boost.
The above image says it all. On the left side of the image are the end of the inlets where they connect to the turbos. You can see how the piping bottlenecks at the turbo connection. For comparison, the below image shows the VRSF stock location silicone inlets.
N54 Inlets Horsepower Gains
Power gains with inlets highly depend upon tuning and boost. An N54 running stock boost would likely only pick up a few horsepower. However, gains up to ~50whp are possible with aggressive tunes maxing the stock turbos. The general idea is the more boost you're running the more gains there are to be had. Many modded, FBO N54's run in the ballpark of 15-20psi. If your N54 is in that range the expected horsepower gains come in around 20-30whp.
Torque is really where you'll see drastic gains. Expect gains of ~30-50 wheel torque. However, additional gains may be had for those pushing the stock turbos towards their absolute limit.
N54 Outlets Horsepower Gains
Again, the same concept applies. Higher boost and more aggressive tuning will result in more impressive results. Expect horsepower gains in the ballpark of 10-25whp on most applications. As with N54 inlets, torque gains will be most impressive. Expect to pick up about 20-40wtq.
N54 Inlets & Outlets Horsepower Gains
This should be easy, right? Inlets pick up about 20-30whp and outlets pick up about 10-25whp so overall you should expect roughly 30-55whp. It's more or less correct. However, don't anticipate picking up 50+whp unless you're pushing 20+psi and holding a lot of boost on the top-end. The gains with inlets and outlets individually are generally greater than when combined. Overall, gains of 30-40whp are likely realistic for most.
This is definitely true for torque. The lower end of the combined numbers are likely realistic. Most N54's running in the 15-20psi ballpark should expect to pick up about 40-50wtq. This post shows a great comparison of a dyno before inlets and outlets, with inlets only, and with both installed. Note - this is on a custom tune running E60 fuel and just north of 20psi. Therefore, those on more conservative OTS tunes shouldn't expect gains quite as impressive.
N54 Inlets Upgrades - OEM Location
OEM location inlets are typically 2" silicone inlets. Additionally, most N54 inlets offer the option of a 1.75" or 2" connection to the turbochargers. OEM turbos have a 1.75" "snout", however many claim the larger 2" diameter still clamps down fine. If you have plans to upgrade turbos in the near future we recommend the 2" connection. However, the 1.75" connection will be the best fitting if you have no plans to upgrade in the near future.
As the name suggests, these inlets reside in the OEM location. Simply pop the old inlets off and install the upgraded N54 inlets. We'll provide a few great options below:
1. VRSF High Flow N54 Inlets
We recommend many of VRSF's products for their excellent balance of price, quality, fitment, and performance. Their stock location N54 silicone inlets are no different. These are standard 2" upgraded inlets with the option for a 1.75" or 2" turbo connection. Additionally, the inlets will work with any intake that fits the OEM inlets. For $79.99 you can add a set of dual cone filters if you do not already have upgraded intakes.
Buy Here: N54 VRSF Inlets
2. Masata N54 Silicone Inlets
Masata is our International manufacturer of choice. Their upgraded inlets come in both stock 1.75" sizing and larger 2" sizing for upgraded turbos. Their inlets are made from high quality reinforced silicone and offer a big flow improvement over stock, offering up to 30whp gains.
Masata is based in the UK so this is a great option for people not looking to pay high shipping costs importing US brands. Masata's product offerings are just as high quality as both BMS and VRSF.
Buy Here: Masata N54 Inlets
3. Burger Motorsports N54 Silicone Inlets
Burger Motorsports (BMS) are well known for their popular JB4 tunes. They also offer some other excellent products, such as high flow silicone inlets for the N54. BMS' inlets are basically identical to the VRSF option above. It's simply another affordable choice for stock location inlets.
Buy Here: N54 BMS Inlets
N54 Upgraded Inlets - Relocated
This is a slightly different route to go. We're keeping it separate since relocated inlets do offer an additional benefit. N54 relocated inlets move the intakes to the passenger side of the vehicle. Why does that matter? Well, relocated intakes actually shorten the length of the intake tract. A shorter intake tract assists in improving engine response and reducing turbo lag. However, it's unlikely to result in any noticeable differences. The reduction in length will help, but it's a minimal reduction in length when compared to the entire N54 intake tract.
Additionally, relocated inlets are typically 2.5" in diameter. However, the larger diameter is unlikely to provide any benefits as compared to the smaller 2" diameter of the stock location inlets. These inlets are also a bit more challenging to install and require moving the coolant reservoir and vacuum canisters to the drivers side. It's a solid option for anyone who prefers the aesthetics. However, we believe the OEM location inlets are likely the best option for most. Nonetheless, below are a few solid options if you're set on relocated inlets.
1. VRSF Stainless Steel N54 Relocated Inlets
Again, VRSF offers excellent products for the price. Note - the dual filters ARE included with the inlet kit. These inlets are a great option for anyone looking for relocated inlets with the added security of stainless steel piping. Our primary concern would be the piping getting pretty hot and causing higher intake temps. Silicone inlets generally work well as they are pre-turbo and not subjected to boosted pressures. As such, we recommend the next silicone option over this one. However, if you're in love with the stainless steel idea look no further.
2. VRSF N54 Relocated Silicone Inlets
This is essentially the same option as above just with silicone piping rather than stainless steel. Filters are also included with this kit. Again, we prefer the silicone inlets over the stainless steel inlets.
Buy Here: N54 VRSF Silicone Relocated Inlets
N54 Upgraded Outlets
Finally, moving onto turbo outlets. There are both silicone and metal options for outlets, as with the relocated inlets. However, we personally prefer the idea of metal turbo outlets on the N54. Unlike inlets, the turbo outlets are subjected to the boosted pressure. Silicone is still strong and unlikely to give out even under heavy boost. We know RB turbos sells silicone inlets with their Game Finisher turbos which have already shown to make 680+whp. So far, we haven't heard of any issues with those silicone outlets. However, some N54 owners have experienced issues with other silicone outlets.
1. VRSF N54 Aluminum Outlet Upgrade
As with the OEM location inlets, these outlets feature a 2" diameter. We really like this option from VRSF due to the aluminum design. Per VRSF, "After extensive testing, we've discovered that using aluminum over silicone not only offers a more reliable solution but it also allows us to increase the size of the outlet which increase flow, all without sacrificing fitment." Great option and at $179.99 it's tough to recommend anything else.
Buy Here: VRSF N54 Aluminum Turbo Outlet
N54 Upgraded Inlets & Outlets Summary
Factory inlets and outlets on the N54 engine are highly restrictive when pushing the limits of the stock turbos or running upgraded turbos. While inlets won't hurt any stock turbo N54 they generally provide the biggest gains at 15+psi, and especially at 20+psi. We believe horsepower gains of 30-40whp are realistic for most N54's running 15-20psi. However, those pushing the limits of the stock turbos may see gains in excess of 50whp. Additionally, a few things we didn't dive into in this post. One, inlets and outlets sound absolutely amazing. Two, they will assist in reducing WGDC and generally help with turbo longevity when pushing the limits.
We run upgraded inlets and outlets on our 2007 335i and absolutely love this mod. The sounds really are incredible. While plenty of inlets and outlets exist on the market (VTT, MMP, Arm, etc) we believe VRSF offers the best options for the money. They also have an option for all customers whether you want OEM location inlets, silicone OR stainless steel relocated inlets, and aluminum outlets. Regardless, it's tough to go wrong with N54 upgraded inlets and outlets if you're running 15+psi.