I used to own a 1990 300zx and had the catalytic converters removed. After this the car not only sounded great but it drove much better. I am thinking on doing the same to my 04 coupe but not sure if any of you recommend using the Stillen catalytic Hi-Flow converters. Here are a few questions I have for those with these converters.
1. Is the noise increase so loud that becomes uncomfortable?
2. Will it pass inspection?
3. Any sensor issues?
4. Did your mpg increase?
5. Would you recommend doing this upgrade?

Thanks to all who read this post.

 

1. Won't be uncomfortable with stock exhaust, might give you some rasp.
2. Not sure about stillens, some HFCs do, some don't.
3. No I don't think the stillens will give you a problem, they have sensor ports.
4. I doubt you'll get better gas mileage
5. Yes, but I suggest you get Berks HFCs instead.

Berks, WILL pass inspection, will give you decent gains and have 0 problems with sensors. I think they are also a little cheaper than stillen's.

Look in our vendors marketplace or the used marketplace. Might be able to find them used, if not one of our vendors will cut you a solid deal.

 

First, I would like to thank you for your super fast response 4DGS. Secondly, I would like to ask you what do you mean with rasp? I was thinking that in the future replacing stock exhaust with a Stillen will this be an issue with this upgrade? Thank you once again and thank you all who read this post.

Fabian
Rio Grande Valley TX.

 

By rasp he means crap *** civic exhaust sound.

 

You can always run straight pipes & toss the converters back on for inspection/emission testing...

 

Berk or Fast Intentions are your best bet. Hit me up if you want some pricing on Berks.

4DGS, Love the avatar

 

^ lol

OP, the stillens are usually pretty loud as a full exhaust, although I don't have much experience with the coupes version. If I were you, I would go Berks Substrate HFCS, with an HKS Hi-power. You'll get decent gains and the HKS looks amazing.

Jackus is right, it's that sound that just sounds crappy. It won't sound like a rice box since it's a 6, but it makes people question what you're saying haha.

To what Matt said, the less restricted you get in the exhaust, the louder and more raspy it will get and more uncomfortable it will get in the car. But test pipes will get you the best gains.

 

Gary

 

I must admit I was not sure what you guys meant with Berks Substrate HFCS. After doing a Google search found the following site: https://g35driver.com/forums/exhaust...est-pipes.html
I guess I will save my money and try to get these for my coupe. I am waiting for a reply from M-Motor Sports but if any of you have some used let me know.
Rio Grande Valley Texas

 

FI HFC!! pricey but worth it

 

1. It's louder but not uncomfortable
2. Yes
3. Yes
4. Dunno
5. Yes

I have fast intentions resonated test pipes and it is awesome!

 

^ you're wrong, most HFC do pass inspections. Test pipes don't. Some times resonated TPs are considered HFCs but they aren't they are just a muffled TP, which is why they fail. Real HFC should always pass.

 

I didn't read through. FIXED
I also don't worry much about inspections as we don't have any here

 

not in CA...

I dont know where the guys that say they pass go.... In CA the smog tech is required to do a visual inspection. If the catalytic converters have been modified they will not pass...

I've said it many times... it has happened to me (with another car).

I suppose if a smog tech is not doing what is required, they wont know.

 

You don't know where? I exclude CA when I talk about anything. Their laws are hella wack, they don't allow tints, exhaust mods etc. Too weird.