Should I install a straight pipe?

Musing over my next build; I was thinking just last week about catalytic converters.

I've seen videos of folks removing them completely, citing increased HP, etc.

I've also seen recently on an advertised-for-sale LJ, a high-performance cat, which allows maximum air flow - like a FlowMaster (?).

I understand there's fed regs which prohibit removal of cats (?).

Anyone running without cats, or running a "high-performance" cat?
 
Jeepers-n-Creepers said:
Musing over my next build; I was thinking just last week about catalytic converters.

I've seen videos of folks removing them completely, citing increased HP, etc.

I've also seen recently on an advertised-for-sale LJ, a high-performance cat, which allows maximum air flow - like a FlowMaster (?).

I understand there's fed regs which prohibit removal of cats (?).

Anyone running without cats, or running a "high-performance" cat?
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I will eventually go to a high flow cat. Something like what flowmaster offers, since they have such a diverse selection.

I’ll add a banks muffler and call it done. I like to hear the 4.0.


However, most people dont.
 
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Jharr_02 said:
Should you straight pipe a 2001 6cyl 4.0L tj? How would it sound ?
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Might want to check out the banks muffler. It sounds great with a high flow cat and or factory cat.

keep your cat(s) and run a nice muffler if you want it to be loud. Dont expect and performance gains from the route you are thinking about taking with this question

The cats and 02 sensors are monitored by your pcm to fine tune your fuel and air. Cutting those items out is a reciepe for loss of performance. With about 190 horspeower at the crank you dont have any room to give up power. Leave what the engineers designed alone. Unless you are smarter than they are and have some magic crystal ball.
 
Fouledplugs said:
I will eventually go to a high flow cat. Something like what flowmaster offers, since they have such a diverse selection.

I’ll add a banks muffler and call it done. I like to hear the 4.0.


However, most people dont.
Click to expand...


A FlowMaster cat and a Banks muffler sounds like the ticket for me.
 
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As the uncle of a child with severe respiratory conditions, please don't remove the catalytic converter :) Save up for a better muffler.
 
Get a straight pipe! And a few curved sections. And a nice good muffler like magnaflow, and weld it all together. And keep the cats on...
 
Good christ these things are loud enough to drive. You own a brick that gets forced through the air, not some sleek sports or muscle car. There's nothing performance oriented that's going to help with that. Keep the cats and get a quiet muffler so you can hear your music once in a while. Don't drive your neighbors out of their minds.
 
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'High flow' will gain you nothing unless you are producing ~500+ hp or have an extremely restrictive system. A TJ has neither. Many a V8 has exhaled thru a similar sized exhaust system. With the low RPMs we turn with a 4.0 there is just no 'need' for any type of performance exhaust.
 
Goatman said:
'High flow' will gain you nothing unless you are producing ~500+ hp or have an extremely restrictive system. A TJ has neither. Many a V8 has exhaled thru a similar sized exhaust system. With the low RPMs we turn with a 4.0 there is just no 'need' for any type of performance exhaust.
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X2, there is zero to be gained. The poor flow of the head is the restrictive element, not the exhaust. Gains in exhaust flow can only be gained at WOT, how often are you at WOT?
 
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