Stock Exhaust Weight

[Captain Snooze]

Originally Posted by Gardus

I'd like to see what happens to the power and torque curve removing the secondary cat and fitting a good catback.

I was under the impression that removing emission control items made the car non-roadworthy.

[serialk11r]

Originally Posted by Captain Snooze

I was under the impression that removing emission control items made the car non-roadworthy.

I assume good catback includes a replacement catalytic converter?

[LivingLegend]

Originally Posted by serialk11r

I assume good catback includes a replacement catalytic converter?

Correct me if I'm wrong but I always thought Catback exhausts replace whatever is behind the catalytic converter but you still would use your original cat...reason for the name catback. Unless your taking about the exhaust companies replacing the original cat with a high-flow cat? I feel like those exhaust would be really pricey...

[Gardus@Supersprint]

As there are two cats emission won't be terribile with just the 1st one.
Obviously the best solution is to replace both of them with a 1st grade sport cats, but to just replace the 2nd with a straight pipe is cheap and won't turn on any CEL as it's not monitored.

[Captain Snooze]

Originally Posted by Gardus

and won't turn on any CEL as it's not monitored.

I wasn't referring to being able to drive the car. I was referring to the legality of driving a vehicle with modified emission controls.

[Gardus@Supersprint]

That depends on the country...
Usually in Italy the pre-cat is enough to pass emission control, if the car is well warmed up.

[RallySport Direct]

Originally Posted by DanPO

I hope Perrin comes out with a straight back (center exit) race pipe with dual tips (no muffler). You would obviously need a different rear lower fascia/valance (whatever it's called) to make the center single exit pipe look nice. Would be cool if there was a carbon fiber option on the rear lower fascia/valance. This setup without a muffler would save a ton of weight and be an aggressive option for track go-ers.

Prova has a center exit system available

We are working on the details with Prova Japan, however this will also include the new lower rear section as well for the bumper.

[Scooby]

Wow, that is ehhhhh.... special

[Turbowned]

Love the Prova exhaust, HATE the diffuser.

[LivingLegend]

^I agree! I don't like how you can see the exhaust pipe from a distance...

[Gardus@Supersprint]

They could have fit just a mesh grill there, at least it would look like a race car.

[russv]

Do any of these exhaust mods require ECU mods as well? I'm concerned that if I make a change it will screw something up.

[Draco-REX]

Originally Posted by russv

Do any of these exhaust mods require ECU mods as well? I'm concerned that if I make a change it will screw something up.

As long as the changes are after the last O2 sensor, you won't need a tune. Generally, a "Cat-back" exhaust is after the cats and therefore won't need to be tuned for.

[Gardus@Supersprint]

Agreed, also, if the reading of the post-cat O2 sensor is correct, regardless of what do you fit, you can leave the ECU alone. The auto-adaptive ability of the ECU will get the A/F ratio, spark advance etc right.
It's rare that a modern ECU of a NA engine is not able to compensate a full exhaust system.

You can have problem if the pre-cat O2 sensor position is very different, for example it happens when you fit a long tube header on a car which had short primary pipes and the original sensor plug very close to the engine. The delay of the reading of the sensor or the different wire lenght confuse the ECU. A good programmer can modify the target of the sensor or the delay of the reading.

This doesn't mean that a ECU remap can't improve the car, as there are also other characteristic of the management that are not subject to auto-adaptation, for example, throttle mapping, rev limiter, valve lift and timing if there is a variable system etc.

[PERRIN_Jeff]

MAF based cars rarely have issues with any kind of bolt on exhaust pieces. The ECU sees more air flow and the car runs the proper air fuel ratio, so its perfectly. Proof of this is when someone dyno's an exhaust and shows the AFR curve before and after. Like this:



No, that is not the catback dyno results, just an example.

[2fast4you]

Originally Posted by RallySport Direct

Prova has a center exit system available

We are working on the details with Prova Japan, however this will also include the new lower rear section as well for the bumper.

I'm not a fan of the muffler and how the pipe is routed, but I wouldn't mind having the rear diffuser and fabricating my own center exit.

[zoomzoomers]

Originally Posted by 2fast4you

I'm not a fan of the muffler and how the pipe is routed, but I wouldn't mind having the rear diffuser and fabricating my own center exit.

Not a fan. Makes it look like the car has got it's junk all exposed.

[2fast4you]

Originally Posted by zoomzoomers

Not a fan. Makes it look like the car has got it's junk all exposed.

Meh... the only people complaining about it will be crossing the finish line after I do.

[DanPO]

I don't like the Prova Muffler set up. I was thinking a race pipe option as well. My brother in law had his BRZ at a performance shop last week where they fabricated intake and various exhaust options... After each part was installed the first initial dyno showed great HP increase levels...(Then the bad news) the ECU quickly remapped everything to only show a 6HP increase with exhaust and intake set up. It appears you can't obtain extra horsepower out of this car without a proper tune.

So hopefully Perrin can come out with something in less than 6 months? Perrin - Have you seen the same results so far? Any thoughts?

[PERRIN_Jeff]

For sure less than 6 months! A sneak peak for you.



Is there HP to be gained? Yes

[Draco-REX]

Originally Posted by DanPO

I don't like the Prova Muffler set up. I was thinking a race pipe option as well. My brother in law had his BRZ at a performance shop last week where they fabricated intake and various exhaust options... After each part was installed the first initial dyno showed great HP increase levels...(Then the bad news) the ECU quickly remapped everything to only show a 6HP increase with exhaust and intake set up. It appears you can't obtain extra horsepower out of this car without a proper tune.

So hopefully Perrin can come out with something in less than 6 months? Perrin - Have you seen the same results so far? Any thoughts?

The Solstice GXP/Sky Redline did the same thing. There's a torque sensor in the driveline that lets the ECU monitor things.

The good news is that this will keep people who mod improperly from destroying the car so badly. I'm eager to see what the tuners uncover when they rack the ECU open. One of the local tuners is going to try and download the ECU on my BRZ this weekend.

[GrimmSpeed]

wow, that prova setup is, um, interesting

Justin