Helix HiFlo cats finally installed
07-01-2005, 01:23 PM
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Helix HiFlo cats finally installed
Well I got the Helix hiflo cats installed today and figured I'd post my early impressions. I didn't do the install myself as it's just too darn hot here in Miami to work outside. I had a small mom & pop auto repair and muffler shop near by so I went over there and had them do it for $70.
The cats had a fitment issue as both right and left made contact with the underside of the car and rattled something fierce. Went around the block and they put it back up in the lift and used a hammer to finnese the ofensive metal into the proper shape to clear the cats well.
On the sound side it has amplified the deep sound of the Fujitsubo exhaust a bit more and there is some rasp from about 3800 rpm to 5000 rpm. Not a lot but you can hear it. I had bought the pricey helix cats becuase they weren't supposed to rasp but they do.
Power wise it seems to rev more quickly to redline once you clear the 4000 rpm mark and the car feels more alive and responsive in that range. Down low and midrange it seems to feel about the same as with the stock cats. Maybe once the ecu adjusts a bit things will get better but right now I feels I gained mostly more sound and not so much HP/TQ.
I am debating whether or not to put the TopSpeed headers in that are sittng at home. Its going to cost ~$400 to install and so far none of the bolt-ons are really impressing me. I know it's probobly time for a reflash but I have to decide the header install/no install scenario first.
By the way re-use the OEM gaskets if possible. The ones that ship with the cats are the same type that my y-pipe came with and those are ready for replacement after only 4000 miles. They look fried especially the one at the connecton beteween y-pipe and mid pipe. I need to find a place that carries compatible gaskets that are like the OEM all metal type.
The cats had a fitment issue as both right and left made contact with the underside of the car and rattled something fierce. Went around the block and they put it back up in the lift and used a hammer to finnese the ofensive metal into the proper shape to clear the cats well.
On the sound side it has amplified the deep sound of the Fujitsubo exhaust a bit more and there is some rasp from about 3800 rpm to 5000 rpm. Not a lot but you can hear it. I had bought the pricey helix cats becuase they weren't supposed to rasp but they do.
Power wise it seems to rev more quickly to redline once you clear the 4000 rpm mark and the car feels more alive and responsive in that range. Down low and midrange it seems to feel about the same as with the stock cats. Maybe once the ecu adjusts a bit things will get better but right now I feels I gained mostly more sound and not so much HP/TQ.
I am debating whether or not to put the TopSpeed headers in that are sittng at home. Its going to cost ~$400 to install and so far none of the bolt-ons are really impressing me. I know it's probobly time for a reflash but I have to decide the header install/no install scenario first.
By the way re-use the OEM gaskets if possible. The ones that ship with the cats are the same type that my y-pipe came with and those are ready for replacement after only 4000 miles. They look fried especially the one at the connecton beteween y-pipe and mid pipe. I need to find a place that carries compatible gaskets that are like the OEM all metal type.
07-02-2005, 06:36 AM
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Hmm. So some modification is required for the Helix cats ha? That was my first choice too; But I want one that will simply bolt one with absolutely no modifying. Any recommendations?
07-02-2005, 10:36 AM
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Cehome,
The mod is not really much. It took about 2 minutes of light hammer work per side to provide clearance. The area that has contact is double walled so you are basically just pushing the outer layer in a bit.
The rasp, eventhough very subtle is my biggest disappointment. Gruppe-S which is where I got these made it a point to mention the "no rasp" feature so maybe it just varies per car.
We'll see how performance goes as the ecu has time to adjust to them. At this point though I think I am going to forget about headers. The cats increased the noise to a level I barely find acceptable for my taste. I fear the headers will be over the top and I'll end up with a car I don't want to drive everyday. Plus i don't believe the performance payback will be there given the cats so far don't seem to be doing much. At least not that I can really notice.
The mod is not really much. It took about 2 minutes of light hammer work per side to provide clearance. The area that has contact is double walled so you are basically just pushing the outer layer in a bit.
The rasp, eventhough very subtle is my biggest disappointment. Gruppe-S which is where I got these made it a point to mention the "no rasp" feature so maybe it just varies per car.
We'll see how performance goes as the ecu has time to adjust to them. At this point though I think I am going to forget about headers. The cats increased the noise to a level I barely find acceptable for my taste. I fear the headers will be over the top and I'll end up with a car I don't want to drive everyday. Plus i don't believe the performance payback will be there given the cats so far don't seem to be doing much. At least not that I can really notice.
07-05-2005, 05:13 AM
#6
The key to installing these is in the exhaust. I installed them and had contact on one side but not the other. I then adjusted the exhaust and was able to get the other side not to rub. It just takes some adjustment like all things do. I love mine, but I have the Injen exhaust. I love the full polished setup from the manifolds back. Makes you want to put mirrors for under the car at car shows.
07-05-2005, 03:22 PM
#7
ZinMiami,
Sorry your not 100% happy with your HF cats...
Mine installed fine with some adjustments... Yes, I too hammered the underbody with a mallet where they made contact. But like you, it took me 5 minutes literally. I also bought a U bolt with rubber spacer and connected them to the OEM brace. Took about 30 minutes to get it all to work out and about an hour to install them.
Overall I am very happy with the HELIX HF cats. I know feeling power is subjective, but with a few mods on the front side and headers and HF cats on the back side, there is a differnece...a BIG difference IMO. My car does not feel the same as it once did. I've taken rides in stock Z's and a 510whp Z. It definitely becomes a differnet animal between 3500 and 6000k. To give you an example...I can feel it pull in 6th when going 60 and flooring it. I couldn't feel that when it was stock. I get a slight bit of rasp between 3-4k, but it's very minimal. I do have a stock exhaust though.
I only did the headers because I did the install myself and I paid around 450 for everything including a 2k coating. Now, if I paid 600 or more for headers plus another 400 for the install, I would second guess it. That's just my .02cents, but if you have the money it's worth the small n/a gain.
Zquicksilver
Sorry your not 100% happy with your HF cats...
Mine installed fine with some adjustments... Yes, I too hammered the underbody with a mallet where they made contact. But like you, it took me 5 minutes literally. I also bought a U bolt with rubber spacer and connected them to the OEM brace. Took about 30 minutes to get it all to work out and about an hour to install them.
Overall I am very happy with the HELIX HF cats. I know feeling power is subjective, but with a few mods on the front side and headers and HF cats on the back side, there is a differnece...a BIG difference IMO. My car does not feel the same as it once did. I've taken rides in stock Z's and a 510whp Z. It definitely becomes a differnet animal between 3500 and 6000k. To give you an example...I can feel it pull in 6th when going 60 and flooring it. I couldn't feel that when it was stock. I get a slight bit of rasp between 3-4k, but it's very minimal. I do have a stock exhaust though.
I only did the headers because I did the install myself and I paid around 450 for everything including a 2k coating. Now, if I paid 600 or more for headers plus another 400 for the install, I would second guess it. That's just my .02cents, but if you have the money it's worth the small n/a gain.
Zquicksilver
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07-05-2005, 07:16 PM
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Thanks for the encouragement Z. I am going to give things time before I decide to go ahead and install the headers or leave things as is. I worry that the rasp and noise may get beyond my taste with the headers. We'll see!
07-05-2005, 09:16 PM
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Besides believing they had "no rasp", why else did you choose helix over RT or Crawford, just curious because I am pondering some cats as well. This may sound stupid, but could you guesstimate how much louder it is with the cats, i.e. 25% or 50%? I have nismo exhaust, which is very quiet, I got it because at that time I was certain I was going NA and knew other mods would increase the sound!
07-06-2005, 08:06 AM
#10
UCLAzzz,
I bought the Helix over the other two only because of the 200 cell metal substrates. I read that some who had the RT's had problems with internals collapsing. I'm not sure if they have improved upon their internals or not? Crawford would have been my second choice, but again, at the time I was unsure what kind of internals they had. The UR high flows sound like they're good too. Warranty, supposedly no rasp, look kind of stock, I would consider these also.
I would say with my n/a mods it's about 25% louder now. It sounds like stock when just cruising, but when you get on it... it sound nice
Quick story, last night I had this guy in front of me reving his (99 or 00) M3 with some aftermarket exhaust when I pulled up behind him in a normal manner. I was like...what in the hell?? Fine, it's nice a cool out and I'm feeling frisky. So we both turn left into a nice straight stretch. I let him get a little ahead of me on the right. He revs and takes off! I do the same but pull on him real quick, then take off thru second and third. He's just shuts down after he realizes he's getting spanked
I've had two guys do this now since I've put my headers and HF cats on. I think the car sound a little meaner now from the front, especially when you get on it. I've had a guy in an M5 and a guy in a S4 with HRE's roll their window down first and tell me nice ride man...car sounds gooood! I'm usually a little shocked and just say, yea you too...
There are a few threads out there with sound clips and mods. Here one...
http://www.350zmotoring.com/forums/s...ight=magnaflow
Good luck,
Zquicksilver
I bought the Helix over the other two only because of the 200 cell metal substrates. I read that some who had the RT's had problems with internals collapsing. I'm not sure if they have improved upon their internals or not? Crawford would have been my second choice, but again, at the time I was unsure what kind of internals they had. The UR high flows sound like they're good too. Warranty, supposedly no rasp, look kind of stock, I would consider these also.
I would say with my n/a mods it's about 25% louder now. It sounds like stock when just cruising, but when you get on it... it sound nice
Quick story, last night I had this guy in front of me reving his (99 or 00) M3 with some aftermarket exhaust when I pulled up behind him in a normal manner. I was like...what in the hell?? Fine, it's nice a cool out and I'm feeling frisky. So we both turn left into a nice straight stretch. I let him get a little ahead of me on the right. He revs and takes off! I do the same but pull on him real quick, then take off thru second and third. He's just shuts down after he realizes he's getting spanked I've had two guys do this now since I've put my headers and HF cats on. I think the car sound a little meaner now from the front, especially when you get on it. I've had a guy in an M5 and a guy in a S4 with HRE's roll their window down first and tell me nice ride man...car sounds gooood! I'm usually a little shocked and just say, yea you too...
There are a few threads out there with sound clips and mods. Here one...
http://www.350zmotoring.com/forums/s...ight=magnaflow
Good luck,
Zquicksilver
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