Louder, lighter and faster.

Just about every day on Facebook, the question is asked:

"What is a good exhaust system and what will it sound like on my 86?"

It's a fair question to ask for a new owner. It is one of those mods that you really want to do on a stock 86 because they are quieter than your grandmas corolla (at least from the outside).

The purpose of this blog is to help people choose an exhaust for their primarily street driven exhaust, a zero-compromise track-only exhaust will not be suitable for road use, at least not in Australia with our defect hungry police force.

Reasons to mod the exhaust system:

Sportier exhaust note
Increase power/torque
Weight savings
Aesthetics

Before we move on to modding lets look at each exhaust component of the 86.

Header (the bit that attaches to the engine directly)

Overpipe - It's called an overpipe because it goes over the steering rack. Go figure. You will also be "over it" quite quickly when trying to replace this with 2.5"+ one.

The front pipe is between the overpipe and cat-back - not sure why they call it the front pipe as it's behind the engine, but lets not get caught up on that.

Cat-back, it's called a cat-back exhaust because it goes behind the cat.

IS BIGGER BETTER?

Well that depends; is your car turbo charged or naturally aspirated? Is your intention to make it loud or go faster?

N/A cars:

N/A cars utilize exhaust velocity (not backpressure) in the collector to aid in scavenging other cylinders during the blowdown process. It just so happens that to get the appropriate velocity, you have to squeeze down the diameter of the discharge of the collector (aka the exhaust), which also induces backpressure. The backpressure is an undesirable byproduct of the desire to have a certain degree of exhaust velocity. Go too big, and you lose velocity and its associated beneficial scavenging effect. Too small and the backpressure skyrockets, more than offsetting any gain made by scavenging. There is a happy medium here.

JUST REPLACE THE HEADER AND ADD E85 FOR SKIDS

A stock 86 can put down anywhere between 100-110 rear wheel KW (135-150hp). The most critical upgrade for N/A and supercharged engines is the exhaust header, a well designed header with a proper tune and E85 (I recommend this 110% if its easily available to you) can give you as much as 130-140 rear wheel KW (180-190hp). Torque increase will also be substantial across the entire rev range but more noticeable with conversion to E85 fuels. I tested this on my car before going turbo with a cheap set of headers (TOG) and E85 my car made 132 KW at the wheels at the 999 Dyno Day in Brisbane.

The rest of the exhaust system is not going to net you any gain on a non turbo engine, it will just make it sound louder/sportier. Which is not a bad thing at all!

Turbo:

For turbo cars, you throw all that out the window. You want the exhaust velocity to be high upstream of the turbine (i.e. in the header). The idea is to get the exhaust velocity up quickly, to get the turbo spooling as early as possible. Here, getting the boost up early is a much more effective way to torque than playing with tuned primary lengths and scavenging. The scavenging effects are small compared to what you'd get if you just got boost sooner instead. You have a turbo; you want boost. Just don't go so small on the header's primary diameter that you choke off the high end.

Downstream of the turbine (aka the turboback exhaust), you want the least backpressure possible.The general rule of "larger is better" (to the point of diminishing returns) of turboback exhausts is valid. Here, the idea is to minimize the pressure downstream of the turbine in order to make the most effective use of the pressure that is being generated upstream of the turbine. Remember, a turbine operates via a pressure ratio. For a given turbine inlet pressure, you will get the highest pressure ratio across the turbine when you have the lowest possible discharge pressure. This means the turbine is able to do the most amount of work possible (i.e. drive the compressor and make boost) with the available inlet pressure.

BIGGER IS BETTER FOR TURBO

As for 2.5" vs. 3.0", the "best" turbo-back exhaust depends on the amount of flow, or horsepower. At 250 hp, 2.5" is fine. Going to 3" at this power level won't get you much, if anything, other than a louder exhaust note. Anything more in HP start looking at 3"+.

My turbo car uses an AVO turbo manifold, a 2.5" overpipe, a modified factory front pipe with stock 2nd cat and resonator. The rest of my exhaust system is custom with a primary single exist muffler at the back. It was not seen as a restriction at the power levels I was chasing. (I will include a full build on my own 86 in a future blog post).

unequal length vs equal length header

UEL Headers require you to get a proper tune, do not get o2 spacers to bandaid the problem, visit your local tuner and get it set up correctly for proper gains and no CEL.

EL headers may not give you a CEL straight away but I still recommend getting a tune as above.

Rally Sport Direct does a good job of explaining the differences in the video below:

HOW DOES IT SOUND?

I'm going to keep this short and sweet, all UEL's sound about the same as each other depending on if they have a CAT built in or not, the same goes for EL. Let's listen...

TOMEI UEL:

TOMEI UEL FROM EXTERIOR/INTERIOR

TOMEI EL:

TOMEI EL Cabin:

ACE A350 EL REVIEW/RESULTS:

Ultrex Performance 86/BRZ UEL Headers and Catback: Budget setups can still sound ok!

CAT-BACK EXHAUSTS

The Invidia R400:

Invidia Q300:

Invidia N1:

HKS HiPower Spec-L:

Tomei Expreme Ti Type-60R:

XFORCE TOYOTA 86 2.5" and 3" Performance Full Exhaust Comparison:

There are so many exhausts to chose from for our cars so if you think it would benefit the community to list another one let me know and I will add it to the list!