# My Introduction

**URL:** <https://forums.speedlife.net/t/my-introduction/247361>\
**Category:** Shift518 Off Topic\
**Created:** [October 6, 2009, 3:15pm UTC](https://forums.speedlife.net/t/my-introduction/247361 "2009-10-06T15:15:49Z")\
**Posts on this page:** 1\
**Showing post:** 29

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**Author:** ![swaiknow](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/swaiknow/32/6359_2.png) [@swaiknow](https://forums.speedlife.net/u/swaiknow)\
**Post date:** [October 10, 2009, 12:57pm UTC](https://forums.speedlife.net/t/my-introduction/247361/29 "2009-10-10T12:57:31Z")

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> [@well might as well post up new system](https://forums.speedlife.net/t/well-might-as-well-post-up-new-system/24172/13):
>
> EGR- exhaust gas recirculation
> 
> The design of the Mazda 6s EGR system puts the tube of the EGR directly in the middle of the intake tract. Thats bad business. Basically it blocks the airflow to the cylinders. This compounded with a decently bad design of an Intake Manifold causes 2 issues.
> 
> 1. one of the 2 cylinder banks will run significantly leaner than the other. How significant are we talking here?  
> –it has been documented that there is about a 5%-7% difference in fuel trims between the front and rear banks.
> 
> **now on a stock motor it probably wont hurt it in the long run. but most of us owners tend to enjoy modding our rides and getting more power. Again 5-7% may not sound like a lot. but that could be the difference of you keeping your 12.2 AFR in one bank…and leaning out to 13.0AFR+ in the other. then boom**
> 
> 1. it blocks some airflow all together. restricted airflow=power lost

so what makes it optimized?

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