Downpipe Installation Instructions

[Mspeed3]

I will agree that the catback alone doesnt yield a lot of power, but combined with dp,intake and racepipe it helps with exhaust flow. Im 3" from turbo back with no cats. Car is amazingly fast!

 

[dkswim]

The Mazdaspeed 3 stock exhaust is 2.25 to 2.75, as said before, I highly doubt the stock catback is going to make a difference , only exhaust note......After the downpipe and midpipe is opened up, the catback size is good enough for our little motor.

should state little turbo

the factory cat back is big enough for stock turbo and mabe some of the slightly bigger turbos yes opening up the exhaust will add power but there comes a point when you no longer gain anything worthwile a 5 in coud flow more then a 3 in but our torbo is not maxing out the 3 in so why have the headache of trying to fit a 5 in when 3 in would work. not stating someone is trying to use a 5 in just speaking genericly the.

 

[AutoXRacer]

The Mazdaspeed 3 stock exhaust is 2.25 to 2.75, as said before, I highly doubt the stock catback is going to make a difference , only exhaust note......After the downpipe and midpipe is opened up, the catback size is good enough for our little motor.

The tip might be 2.75"...but the overall tubing is ~2.25".

Regarding my personal experience, swapping out my CBE yielded me more fuel demand out of my engine. Don't know what else to say. I got data to back that up. I guess I must have a freak of a car... (scratch) (dunno)

Others have agreed with me that my stock CBE was my bottle neck of my flow. I'm not saying I yielded 10-20HP, but I did feel a difference in with throttle response, turbo spool, and power at high RPMs.

Think what you want...but these were my personal experiences with my CS CBE... (2thumbs)

 

[bnoon]

Be careful when removing the WD O2 and the 2nd O2...you will strip the threads!! Use plenty of penetrant and you'll have to loosen and tighten, loosen and tighten, basically working it out slowly... This is the worst part of the job; at least for the WD O2.

In my opinion, the CBE is definitely worth it. The stock piping is tiny compare to an upgraded DP. The CBE was the last mod in my car and it made a huge difference...to the point that if affected my AFRs...

(poke) Why will the threads strip??? I've taken out tons of O2's and never had any strip out before...

 

[AutoXRacer]

(poke) Why will the threads strip??? I've taken out tons of O2's and never had any strip out before...

Ooooh, you haven't heard... According to quite a few techs, Mazda did some magic to the MZR engines and the O2 sensors. Basically, I removed mine with less than 5K miles on my engine and it was seized in there. It felt like it got installed cross-threaded. You could not just unthread it...if you put torque on it, say goodbye to the sensor. I was careful and used plenty of penetrant and still ended up messing up my threads slightly. Trust me when I say you CAN"T force it at all!!!!! Its like the threads are made out of butter. The longest part of this job is removing the O2 sensor and putting it back in. You can't just screw the O2 sensor back in either, you have to work it back and fourth, screw, unscrew, etc... Biggest pain in the ass...

Check these threads out:
http://**************************/f...emove-o2-sensors-without-messing-them-up.html (just replace the ***** with mazda-speed-forums without the "-")

http://www.mazdas247.com/forum/showthread.php?t=123692938&highlight=sensor+damage

 

[dkswim]

what they made it one time use........

the problem is they put it in w dry threads

 

[markharrison]

Ok, Cp-e downpipe and exhaust on order. I will report on the install when I get them in about a week.

I installed a COBB SRI today. Very nice unit, great quality and works like a damn.

 

[Aaron@JSC]

This topic has been beat to hell on previous cars that I have had, which were NA. I'll be generous and say maybe 1-2HP if any at all, for a catback exhaust system on this car.

Restriction and back pressure are a whole different ball of wax on a N/A car than a turbo car. On a turbo car the turbocharger provides sufficient back pressure to maximize torque output. On a N/A if you just run an open header, you can actually lose torque.

It is a fact of physics that the most efficient exhaust system for a turbocharged car is simply a cone shaped dump tube post turbo, anything beyond that is just a function of sound, routing and emissions standards. Tubing bottlenecks, resonators, mufflers all cause additional back pressure and restriction in the exhaust. It doesn't make a huge difference but it is still there.

The idea of an exhaust system gaining a significant amount of power on your 'butt dyno' is the effect of the turbo spooling sooner and that jolt of torque hitting harder and earlier. The car may not make a significant increase in power on a dyno, but it feels much faster to the driver.

How a car could could have AFRs effected by the exhaust post DP doesn't make and sense, there must be more variables involved like more boost coming on from the freer flowing exhaust.