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Hey guys. Just curious. I've got pypes axlebacks, a steeda CAI and bama 93 octane tune. I've been thinking about having an exhaust shop cut out the middle section with the resonators and restrictive H pipe and replacing it with 3" and a better X or H pipe. So my question is, even with keeping the stock cats, would i need a revised tune with the bigger mid pipe? Thanks!
 

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It's not me, it's you.
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Changing the H pipe might trip your check engine light. A tune would prevent that. Also, be careful about hacking up your exhaust you could create a drone condition and that is the most annoying sound.
 

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You are gonna be wasting your money if you replace the stock mid pipe and leave the cats. These cars are really restrictive with the cats and they won't tune for mid pipes anyhow. Like Primer said the tune will help with the check engine light.
 

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Anything you do to the exhaust AFTER the rear 02 sensor WILL NOT require a tune PERIOD.... The stock H pipe is not restrictive!!!!!! The H-pipe is simply there to balance the exhaust pressure. It has been shown on the dyno, that CAT-BACK systems are great for improving sound, but only make 2 or 3 more HP. Go ahead and cut out the resonators if you want. I would not remove the Cats, unless you go FI, or if you drag race and use a 2-step.
 

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Loc: Austin,TX
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Anything you do to the exhaust AFTER the rear 02 sensor WILL NOT require a tune PERIOD.... The stock H pipe is not restrictive!!!!!! The H-pipe is simply there to balance the exhaust pressure. It has been shown on the dyno, that CAT-BACK systems are great for improving sound, but only make 2 or 3 more HP. Go ahead and cut out the resonators if you want. I would not remove the Cats, unless you go FI, or if you drag race and use a 2-step.
Why would you not wanna go cat less on these 5.0s if you are looking to add HP? A cat less X pipe has shown gains as good as LTs for some people. If the gains aren't an issue,you have inspection in your county or you just don't want the noise or smell then I agree with keeping the cats.
 

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Removing cats first of all is illegal , and i have seen on other Forums were they did dyno pulls with and with out cats and showed only 1 and 2 HP gains. The stock exhaust is very good, performance wise. After all, you have a small C.I. motor, with big 2 3/4" pipes On my car i installed a 2-step, I did not want to damage the cats , so i installed a catless H for racing and did not see any gain in ET or MPH.
 

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Loc: Austin,TX
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Removing cats first of all is illegal , and i have seen on other Forums were they did dyno pulls with and with out cats and showed only 1 and 2 HP gains. The stock exhaust is very good, performance wise. After all, you have a small C.I. motor, with big 2 3/4" pipes On my car i installed a 2-step, I did not want to damage the cats , so i installed a catless H for racing and did not see any gain in ET or MPH.

Removing cats is not illegal in every state. Strange....I havent seen any threads with complaints about only gaining 1 to 2 HP by losing the cats. Everything ive seen has been positive. Dyno'd mine with tune,cai and Roush exhaust (catted stock mid pipe and headers) and got a whopping 374?? I just install LTs,OR X and Boss mani and will probably get it dyno'd in FEB at our dyno day. I will post results later. Hope it turns out well.


Edit: These threads you speak of...are they talking about 05-10 3V cars? Removing the cats on the 5.0s makes a huge difference...not the same as the 3v. The OP has a 4V.
 

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removing cats is against FED law. makes no difference if your area requires testing or not. And most people removing cats are seeing HP gains because of there tune, The tests i am referring to were done stock w/cats vs stock w/o cats. The only way you can compare is to leave everything the same, and test w/ cats and then remove the cats. Once you mod it is very difficult to know what part is responsable for the gain. Last year 5.0 mag did a bolt on test, and they saw higher HP gains with all the parts installed, than they saw doing the test 1 part at a time and adding the gains up.
 

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CaptainBeyond said:
Hey guys. Just curious. I've got pypes axlebacks, a steeda CAI and bama 93 octane tune. I've been thinking about having an exhaust shop cut out the middle section with the resonators and restrictive H pipe and replacing it with 3" and a better X or H pipe. So my question is, even with keeping the stock cats, would i need a revised tune with the bigger mid pipe? Thanks!
I did this at first, it is the cheap way for a reason. I had to redo my whole exhaust because some exhaust shop cut an pieced some hack job together and I paid for it the long run with leaks and stuff like that. If you want to save on money do like I did, magnaflow xpipe and pypes super system it was worth every penny
 

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The Blue Dragon
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I've gotta agree with DDTCM on this, never heard of no gains when removing cats. of course you will not get gains without tuning for it, that is true for 99% of engine/exhaust mods that tuning is necessary. but take a 5.0 with just a 93 tune, now take a 5.0 with a 93 tune, and tuned for no cats, still ~15 hp gain.

I can't argue that it's not illegal though
 

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GrabberBlue5.0 said:
I've gotta agree with DDTCM on this, never heard of no gains when removing cats. of course you will not get gains without tuning for it, that is true for 99% of engine/exhaust mods that tuning is necessary. but take a 5.0 with just a 93 tune, now take a 5.0 with a 93 tune, and tuned for no cats, still ~15 hp gain.

I can't argue that it's not illegal though
Ya I haven't heard of not gaining any HP when taking off your cats either. Lol. But I did feel a little torque loss on the low end. But top end feels better. So basically you gotta sacrifice one thing for another thing
 

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AmericanMuscle.com
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Hey guys. Just curious. I've got pypes axlebacks, a steeda CAI and bama 93 octane tune. I've been thinking about having an exhaust shop cut out the middle section with the resonators and restrictive H pipe and replacing it with 3" and a better X or H pipe. So my question is, even with keeping the stock cats, would i need a revised tune with the bigger mid pipe? Thanks!
CaptainBeyond,

This is definitely a quick/affordable mod that will show some gains. When you do a custom exhaust set up, sometimes you do run into leaks, noises etc.. Your other option would to go with an Off-Road X-Pipe. This will get rid of your cats and give you a straight through design. With a tune on the 11+ GT's we've seen gains of 15+RWHP from this set up!

I hope this helps, let me know if I can be of any assistance!

-Dan
 
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