Having a Phat exhaust -

[The Running Man]

So, i wondered as many people do, what exactly are the benefits of a fatter, wider, straighter exhaust?

Does having a big phat pipe sticking out the tail end make a tangible difference compared to a smaller peashooter that winds its way around the back side of the car?

Yes.

My car hasd a JDM Apexi Hayabusa which is a single exit with pipework at 76mm increasing to the tail.

I also have an exhaust bung and a boost controller with which to test the setup.

being MOT day, i popped the bung into the exhaust and tried a run on the motorway. The acceleration seemed much more pedestrial than usual, and boost peakes at about 0.72 bar (Blitz DBSC).

Finish MOT, remove bung, drive home and voila, same piece of road etc same conditions, car now gets to 0.84 bar with no alterations or tweaks. Same EBC settings.

So what does this mean?

Exhaust bungs are bad. its official. MOT testing Yes, performance, No.

Fatter, straighter exhauists will help you to produce more power by reducing the pressure on the exhaust gas outflow, IF the existing diameter or smallest diameter is actually blocking or inhibiting the boost escaping quickly enough.

Sounds simple, but i was actually shocked at just how much the bung reduced the forward accel of the car itself.

 

[The Running Man]

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I'm guilty for having a phat exhuast, get no end of ribbing from the guys at work.

Japspeed cat-back on a 1.3 Starlet turbo, innit blad.

EDIT: To be fair, when I first got it I thought it looked a bit too big, but hey, it was a brand new system practically for 100 notes, and I needed some form of exhaust to get it on the road!

Hmm at work they all tell me my exhausts getting louder. It's not, it's the solid mounts blud.


But yes of course not every car can benefit, but definitely those pushing a lot of fumes out the back.

it eases the restriction on the turbo and allows it to work more easily to produce the same, or more power.

Piping like this