straitpipe, backpressure info help
Herp Derp Jerp

Joined: Nov 2011
Posts: 18,251
Likes: 17
From: Parham, ON
Year: 1999
Model: Cherokee
Engine: 4.0L OBD-II
Removal of or hollowing out your cats is a violation of federal law and banned on this forum. There are a lot of vendors that sell high-flow cats that can be welded in place.
Regarding running without a muffler, there are various requirements in various jurisdictions. Some require the exhaust to be dumped outside of the cab, so you must run it all the way back. Others state that all vehicles must be affixed with spark-arresting mufflers, such as national parks run by the Forest Service.
Do a 3" stack above the roof line.
Regarding running without a muffler, there are various requirements in various jurisdictions. Some require the exhaust to be dumped outside of the cab, so you must run it all the way back. Others state that all vehicles must be affixed with spark-arresting mufflers, such as national parks run by the Forest Service.
Do a 3" stack above the roof line.
Back pressure is a myth. Period.
Its exhaust velocity you want, removing the muffler won't effect it.
As Salad mentioned, discussion of the removal of emission equipment is not permitted.
Its exhaust velocity you want, removing the muffler won't effect it.
As Salad mentioned, discussion of the removal of emission equipment is not permitted.
Herp Derp Jerp

Joined: Nov 2011
Posts: 18,251
Likes: 17
From: Parham, ON
Year: 1999
Model: Cherokee
Engine: 4.0L OBD-II
CF Veteran
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From: San Jose
Year: 89
Model: Cherokee
Engine: 4.0 I6
Herp Derp Jerp

Joined: Nov 2011
Posts: 18,251
Likes: 17
From: Parham, ON
Year: 1999
Model: Cherokee
Engine: 4.0L OBD-II
CF Veteran
Joined: May 2012
Posts: 3,004
Likes: 1
From: Wilmington,NC
Year: 1989
Model: Cherokee
Engine: 4.0
Thread Starter
CF Veteran
Joined: Oct 2012
Posts: 1,277
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From: Orlando/Winter Garden
Year: 1998
Model: Cherokee
Engine: I6
and yeah that last pic with the exhaust comin out and up the back window looks official
im just gonna saw off the muffler and replace it with pipe
there is far more restriction in the cat than what's in the muffler
it will be fine. and basically any engine u deal with that has more than 5 cylinders won't be noticeably affected by no back pressure.
it will be fine. and basically any engine u deal with that has more than 5 cylinders won't be noticeably affected by no back pressure.
Senior Member
Joined: Jan 2012
Posts: 701
Likes: 1
From: DuPage County, IL
Year: 1994
Model: Cherokee
Engine: 4.0L I6 HO





