I was wondering, how's the sound of helix Hi-Flo cats? is there any raspy sound?
I'm still debating over helix hi-flo cats and crawford hi-flo cats. helix is more cheaper than crawford. but if crawford is better than helix in terms of build quality and sound, I'll get the crawford instead.. So please clearify me about this.

 

https://g35driver.com/forums/reviews/44644-helix-hi-flow-cats.html

 

I have them but they aren't on yet. If you can afford it though, get crawford. I have heard from alot of people that there is some raspy sound between 2,500 and 3k. I just have them becuase I got them used for a way good price. I'll get crawford later on.

 

thanks for the info copbait. So there is a problem with fitment issue? it says that the resonator is too big and cause rubbing against the underbody. How can I fix this?

 

If this is on a coupe you can fix it pretty easily by hammering the underbody of the car to make room for the cat housing. I did that on both sides but I guess I didn't do it enough on the right because I can hear it rubbing when I go into reverse. The left one is fine.

IMO it's not a big deal, and it's just a matter of taking the hammer to the right side when I have a chance to put it on a lift again.

If you are trying to put these on a sedan, I don't think they will fit. The guys at Gruppe's said this first batch of Helix cats most likely won't fit on the sedan without doing a lot of work unerneath to make room. Helix is supposed to be coming out with a smaller cat that will fit the sedan, but not sure exactly when. For those interested check with Gruppe's.

 

I have no rasp with my Helix cats but I've got the stock exhaust. I have heard that all hi-flow cats or test pipes may cause some rasp with aftermarket exhaust though...

 

what exactly do you mean by hammering the underbody? So you get a hammer, hit the underbody and making big dent to get more room for the cats?
I would really appreciate it if you can show me a picture.. picture will explain better IMO.
By the way, for crawford cats, is there such fitment problem?

 

We had to hammer the floorpan -- vic that's pretty much what we did. They do fit the sedan without hammering, just they rub -- too little clearance. with the floorpan hammered all is good though. My check engine light came on again though... grrr.

 

Oh that's good to hear, so the sedan and coupe must be laid out about the same up near the manifold flange.

 

Basically yes. Sorry no pics, but I'm sure you could dig up something on the net of what it looks like under there..

 

thanks.. for the info.. I'm still not sure if I want to hammer my underbody.. just dont feel like want to make any dents under there.
but what about crawford cats? does it have fitment issues? if it doesnt I'll definitely get crawford cats instead of helix.

Ajay, why is your engine light on? I thought that only cat delete pipes cause the engine light on.

 

I think the O2 sensors are getting bad readings. Going to find out later this week...

 

I just installed mine today. They fit fine. I also put on my Stillen exhaust. I can't drive my car yet but just from starting it and going through the rpms a little bit, it's hella hella raspy. It did get alot better after I let it run for a few minutes and warm up though. As soon as my frickin wheels get here I'll be able to tell a little better. I'll try and post a mpeg or something.

 

yeah.. please do post a video clip. So how come some people dont have fitment issues while others have, and how come some people get the raspy sound and other dont?
is it because they install differently?

 

I answered that a few posts back, read again