Straight piping without losing hp or torque

91XJHO

91XJHO

It's never cleaned...
Joined
Apr 24, 2011
Location
Winston - Salem
I have a gas 4.0L High Output engine on my cherokee and going to straight pipe it with a borla xr-1 sportsman racing exhaust. What I was going to do is gut the cat and put a pipe through it, because NC law doesn't require an emissions test, but the exhaust assembly it comes with stock has to be on the vehicle to pass inspection. Make it short, how can I straight pipe my jeep to the exhaust without losing power?

Thanks
 
you could add a $30 turbo muffler (I got mine at Advanced) and you wont have to worry about losing the torque, plus it won't be obnoxiously loud.
 
why in gods name are you spending that much money on a muffler just for noise?

Cherry bomb glass pack and be done with it
 
Why in the hell.do you want to straight pipe a 4.0......that shits annoying out on the trails....hell on the road even. Straight pipin somethin is like spandex....its not a right, you have to earn it........throw ya a thrush welded on there an itll sound decent and be fairly loud
 
A good exhaust can add power and make a 4.0 sound pretty sweet. Straight piping makes it loud, weak, and sound like ass. And I've got to share the roads with you. For God's sake, don't do it. If you do, put the biggest, chromest truck nutz on your bumper so I can see you from a distance.

If you want to get the power back from straight-piping it, I've heard painting the entire thing in Herculiner adds 20hp.
 
My buddy runs the same set up as I'm talking about. It is loud and not obnoxious.
 
Why run a pipe through the cat? Why not just gut it and run the pipe from there? It'll be plenty loud and obnoxious without the added work of running a pipe through the cat. What year is this? If 96 or newer you'll still have to do something about the check engine light that will result from not having the cat. Personally I hate the smell of my vehicle without a cat on it.
 
rattlecanpaint said:
Why run a pipe through the cat? Why not just gut it and run the pipe from there? It'll be plenty loud and obnoxious without the added work of running a pipe through the cat. What year is this? If 96 or newer you'll still have to do something about the check engine light that will result from not having the cat. Personally I hate the smell of my vehicle without a cat on it.
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That's what I'm doing. Gutting the cat and running a pipe through it. To pass inspection in NC you have to have the full assembly of the exhaust from the factory (cat and exhaust) to pass inspection.
 
Waste of time IMO, but I guess I am a purist, if I am not gonna have a functioning cat, you can bet there won't be a gutted cat under the truck, if you are going to do it, do it RIGHT. If you want to remove it all, get someone to mess with the computer or trick the O2 sensor so it will still run fine.

I am also betting if you must remove it, you can find an inspection station that will pass it, there are many I know of that would...
 
As an inspector, I know everything has to be there and "appear" to be functioning. My point was why weld in a pipe through the center of it? Seems like a waste of time. Just gut it and put it back without the innards. The computer is going to set a check engine light because the rear o2 sensors are going to pick up that the cat isn't working and that will fail your state inspection.
 
+1whp is why, duuuh.

that and everyone wants to sound like Dylan's mean Wace Kawra! Hell, that's why WTFab ditched the cat and went to a 10Ga case RockRumblr, just to keep up with the racket making
 
It really isn't all that hard to trick the O2 sensors. I have deleted the cats off of a 2010 civic and spent about an hour tweaking to get the flow right but no check engine lights. I don't understand the straight pipe craze. You have a straight 6 gasser...it is going to sound like a pack of pissed off bumblebee's in the park.
 
Maybe, but odds are the most restrictive part of your exhaust is the manifold. Look into getting a header if you're hell bent on exhaust work.
 
i watched a few vids with a magnaflow hi-flow cat with the magnaflow exhaust like mine. it sounded good
 
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