# high flow cat

**URL:** <https://forums.speedlife.net/t/high-flow-cat/124624>\
**Category:** SON240sx Automotive\
**Created:** [May 19, 2009, 8:22pm UTC](https://forums.speedlife.net/t/high-flow-cat/124624 "2009-05-19T20:22:01Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![240sx\_nismo](https://avatars.discourse-cdn.com/v4/letter/2/3da27b/32.png) [@240sx\_nismo](https://forums.speedlife.net/u/240sx_nismo)\
**Post date:** [May 19, 2009, 8:22pm UTC](https://forums.speedlife.net/t/high-flow-cat/124624/1 "2009-05-19T20:22:01Z")

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hey just wondering wither its better to run with a high flow cat or a punched cat/test pipe. ive heard high flow will give back pressure witch is needed and a punched cat gives none. what should i do?

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**Author:** ![drjeffreys](https://avatars.discourse-cdn.com/v4/letter/d/e9c0ed/32.png) [@drjeffreys](https://forums.speedlife.net/u/drjeffreys)\
**Post date:** [May 19, 2009, 10:08pm UTC](https://forums.speedlife.net/t/high-flow-cat/124624/2 "2009-05-19T22:08:20Z")

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Just put a cat on it… the MTO are happy… People behind you not smelling fuel are happy… and you will ofcourse have no issue passing an etest, or any side of the road e-tests… as for power difference… i noticed much better, more consistant flow with a cat.

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**Author:** ![240sx\_nismo](https://avatars.discourse-cdn.com/v4/letter/2/3da27b/32.png) [@240sx\_nismo](https://forums.speedlife.net/u/240sx_nismo)\
**Post date:** [May 19, 2009, 11:28pm UTC](https://forums.speedlife.net/t/high-flow-cat/124624/3 "2009-05-19T23:28:18Z")

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> [@Off road meet 2 \*\*pics inside\*\*](https://forums.speedlife.net/t/off-road-meet-2-pics-inside/21793/53):
>
> Just put a cat on it… the MTO are happy… People behind you not smelling fuel are happy… and you will ofcourse have no issue passing an etest, or any side of the road e-tests… as for power difference… i noticed much better, more consistant flow with a cat.

yes but i forgot to ad its an s14 witch all come with two cats obd2 and has the down pipe cat on but the cat that comes right after the down piping is punched. if i put on a new one ill be running to cats and im thinking it will slow me down by alot.

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**Author:** ![91S131](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/91s131/32/5732_2.png) [@91S131](https://forums.speedlife.net/u/91S131)\
**Post date:** [May 21, 2009, 8:49pm UTC](https://forums.speedlife.net/t/high-flow-cat/124624/4 "2009-05-21T20:49:14Z")

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a “high flow cat” barely restricts and get rid of the 2nd cat. if you want

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**Author:** ![87s15lt1](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/87s15lt1/32/5706_2.png) [@87s15lt1](https://forums.speedlife.net/u/87s15lt1)\
**Post date:** [May 21, 2009, 9:14pm UTC](https://forums.speedlife.net/t/high-flow-cat/124624/5 "2009-05-21T21:14:43Z")

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KA? run a high flow or even a regular cat.

SR? internal wastegate, punch that shit out. turbo’s need to breathe

External wastegates needs some back pressure, so a high flow is good.