Rat

Theoretical exhaust question:

Our stock header runs cylinder 1 + 4 together and 2 + 3 together. Then these two pairs are joined together so one pipe runs to the rear. Then there is a split back into the left and right mufflers.

Would there be any benefit to a system that runs 1 + 4 together and then runs one pipe to the right muffler. And 2 + 3 together and a second pipe to the left muffler.

So there is a true dual exhaust.

Any exhaust experts out there?

Sabre

I'm not an expert by any means, but I think that the flow that is in place creates backpressure which increases the torque the motor produces.
By splitting the header into a 4-2 only, you lose that effect.

I could be totally wrong on this though.

jeffbrig

I'm sure there would be pros/cons at different rpm ranges. But, the channel where the current single pipe runs down the middle of the car would probably not be able to accommodate two pipes of sufficient diameter, so it's kind of a moot point.

dc2-2-ap1

You would have the room to do it. The Berk UHV exhaust from years ago ran a dual setup. I believe it ran 57mm pipes. So it is possible. You would have to have a custom header made along with the exhaust. My guess would be that it would hurt the car more than it would help. It is a 2.0L 4 cylinder- that is not enough displacement/cylinders to warrant a true dual setup. Single exhausts have been proven to outperform duals. But like all the aftermarket headers, piping diameter, diameter changes, merge points, and other factors play into designing one that works efficiently. This car has been around for 16 years now, and 2 companies in the past 2 years were finally able to outperform the J's header from the beginning ( Ballade Sport and Urge). So there is always room for improvement, it just doesn't come easy and it is never right the first time. If you do it, and want it to be good, plan on redesigning it several times. This will be very time consuming and very costly- even if you had access to a dyno and have the ability to fabricate all the piping.

RedCelica

The simple answer is no. Look up "exhaust pulse." http://www.epi-eng.com/piston_engine...technology.htm

Basically speaking, the header on a straight 4 needs all 4 connected, otherwise the exhaust flow will lose too much velocity too quickly, stagnate, and create a crap ton of back pressure. Not a good idea. Only way around it is to make the exhaust piping smaller in diameter, and then it sounds like buzzing hornets. In other words, all 4 tubes from the block work in sync to create an optimal pulse to get exhaust gasses out, which in turn aids in getting fresh air in.

Manga_Spawn

The Berk UHV split after the cat or test pipe though not at the header. It was also loud as balls and super droney. Their 3 inch headerback was quieter.

dc2-2-ap1

^yes. I brought that exhaust up because someone mentioned there may not be enough room. That exhaust showed that there was enough room. They claimed it flowed like an 80mm, so I figured it would be loud.

Manga_Spawn

Ugh so loud. So drone. I guess the place where space would be a possible issue is right at the header. Running 2 pipes from there may be tough still you get back past the cat. The way to do a true dual is swap in a v6 or v8.

GOGPWS2K

What this guy said.