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      01-10-2017, 07:54 AM   #6
SeanWRT
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Drives: E90 M3 & F87 M2
Join Date: Sep 2015
Location: Shanghai

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It's all about balance of the gain and sacrifice.

A catless system that give you 100% flow and CEL and a smelly car.

You have the option with HJS 200 cell to flow 10% less so you're CEL free and have much less smell to live with.

One step further, a HJS 300 cell (EU6) comes with smog test guarantee and smells the same as stock, with 10% less flow over 200 cell.

Now you think about how 10% flow affect performance. That will have everything to do with your mods. But there's definitely diminishing return in play, meaning going from stock to 300 cell probably get you 80~90% of the gains (dependent of the peak flow demand from you mods) of a cat bypass system. If you can handle CEL, don't care emission and are fine with smell, pursue the remaining gains with catless dp.

Personally never been able to live with smell. To me 200/300 cell sit nicely in between restrictive stock and cat bypass.
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Last edited by SeanWRT; 01-10-2017 at 08:29 AM..
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