One of the first things we noticed on the BRZ/FR-S engine is that the OEM inlet hose could use some major improvements. From the resonator chamber, and the noise generator tube, to the fact its not very smooth on the inside, this for sure was a part that we could make better and make some HP with.
Lets look at the stock part first. You can see below that there are a bunch of extra pieces to the OEM part. You have the sound generator and tube, and the resonator that hang off the hose. Both these parts have huge ports that connect them to the intake track, which means there are huge disruptions caused as the air passes over them. You can see in the OEM part the bellows that are in the middle. The inside of the part looks just like as well, making for further disruptions to the air flow.
Below are some cut aways showing this as well. It's is very clear which hose will flow more air!
We improved the quality of the inside of the hose as you can see, we also improved the overall shape of the hose. Using the below diagram, you can see how the OEM part has a super sharp bend where it connects to the air box. Seeing this as a flaw, we redesigned the hose to have a much smoother more gradual bend. The radius of the bend on the OEM part is 1.5", versus the PERRIN Inlet hose uses a 3" radius!
One last thing we improved was the size of the hose. We made the hose as large as possible while still being able to fit to the OEM air box as well as the throttle body. You can see in the diagram below the differences in the two parts. We made sure that it would suite our future PERRIN 3" intake as well as other future items like bigger cams, 9000RPM Redlines, and even supercharger kits that would utilize the stock part.
In the above cutaways you can see the stainless steel wire that is wound around the inside of our hose. This is important to ensure that the silicone hose NEVER collapses under vacuum. Even the OEM part has ribs and features that keep the rubber from collapsing during high RPM and load. Some competitors may leave this out to save costs, but in our eyes its not worth the sacrifice.
You can see that unlike some available aftermarket Inlet hoses, we didn't just copy the OEM part and make it a dress-up part, we improved it!
What does this all translate to in horsepower gains? This test was done on a stock 2013 BRZ where the only part was swapped was the inlet hose. You can see its worth a few HP across the RPM band with no other aftermarket parts installed. We have seen a solid 5 WHP gain on cars with 2.5" header back exhaust systems installed along with an intake system. The BRZ really seems to like free flowing things like the intake system and inlet hose, when there is a high flow 2.5" header-back system installed!
We may have been the first to show off our prototype and the last one to market, but we do believe that the PERRIN Inlet hose for the BRZ/FR-S is the best one available. With all the time we spent designing, the dyno proven HP, and the fact it looks awesome under your hood, there is no reason to buy any other Inlet hose!