Tomei UEL Header |
Upgrading to an aftermarket header is the most significant way to increase power on a naturally aspirated FR-S/86/BRZ for two reasons - 1) The header is the most restrictive piece of the OEM exhaust system, so swapping it to a more free-flowing unit increases power output more than swapping any other piece in the exhaust system 2) Upgrading to an aftermarket header allows you to jump from OFT's stage 1 engine map to their more aggressive stage 2 or stage 2+ tune (stage 2 for headers with a catalytic converter, stage 2+ for uncatted headers). Gains from an aftermarket header and tune are generally in the range of 20-30 horsepower at the wheels.
When selecting a header for the FR-S/86/BRZ, there are two categories available - equal length or unequal length. Equal vs unequal refers to the length of the exhaust runner for each cylinder. An equal length header means that each of the exhaust runners are the same length. Unequal length means they aren't the same length. Both types have unique characteristics, so choosing which one is right for your build depends on your preferences and priorities.
Equal Length Headers (EL)
- Tends to make the most peak power
- Produces a smooth exhaust note similar to the factory header (the factory header is an equal length unit)
Unequal Length (UEL)
- Sees slightly less peak power than EL headers, but gains more power and torque in the low - mid rev range
- Creates the classic Subaru rumble exhaust note that we all know and love
Since I love the Subaru rumble, and because down low in the revs is where the FR-S needs a power boost the most, I opted to go for a catless Tomei Expreme UEL header.
FIRST IMPRESSIONS | Quality
It isn't difficult to see why the Tomei header is one of the most popular options for the FR-S/86/BRZ. The quality and finish of the Tomei Expreme UEL header is excellent. The welds are fantastic, the mirror-like finish on the exhaust runners is flawless, the flanges are chunky and thick, and the collector is free of any burrs or imperfections. Tomei's headers are more expensive than other options out there, but this is one area of the exhaust where you shouldn't cheap out. The header has a big impact on overall sound and performance, so spending a little bit more to make sure you're getting something good is definitely worth it.
INSTALL / FITMENT
The flat-four boxer engine in the FR-S/BRZ/86 makes header swaps one of the easiest out there. Since the engine is a horizontally opposed configuration, the header and all header bolts are right on the bottom of the motor. Tomei's fitment was perfect and required no adjustments. Had adjustments been needed, Tomei makes it easy by including a sleeve and two small bolts that allow adjustment of the overall header width. The install is about as straightforward as it gets, but there are a few tips that can make things easier:
1- Soak the header studs in PB Blaster overnight. Rusted studs are easy to snap or strip, so an overnight soak is a solid precaution
2- With a UEL header, one of the exhaust runners restricts access to the nut on one of the header studs, making it tricky to tighten. There's not enough space for a deep-well socket, and the stud is too long to use a shallow 3/8 socket. There's not enough clearance for a box wrench either. The best solution that I found was to use a 1/2" drive socket and a 1/2" breaker bar. The 1/2" socket is just deep enough to clear the header stud, and the breaker bar is low profile enough to fit between the runners, allowing you to tighten the bolt a little bit at a time. If anyone has a better way of doing this, please let me know
3- Be careful when you bolt the over pipe back on. It's very easy to bolt it in place and not leave enough clearance between the over pipe and the chassis or the over pipe and the engine. Visibility is limited in this area, so make sure you feel around to check. If there isn't enough clearance, it'll rattle when the engine is under load (may or may not have done this myself and spent way too long trying to figure out why my car sounded broken)
The performance and sound of the Tomei Expreme UEL header is amazing. The power difference from the stock header is immediately noticeable - especially down low. The combination of the header and the stage 2+ tune brings the FR-S to the power level it should have had from the factory... It's unfortunate that you need to do so many modifications to get it there, but hey, that's life.
As one would expect with a catless header, and depending on the rest of your exhaust system, it can be quite loud. Mine certainly was. Since my Greddy Revolution RS cat-back is one of the louder cat-backs on the market, and since my front pipe is catless and unresonated, it was too loud for my tastes. The winning combination for me was to put the stock front pipe back on, which eliminated the all rasp and brought volume levels back to an acceptable level without any noticeable loss in power.
All in all, the Tomei Expreme UEL header was a great purchase - one that I should've done a long time ago.