They will.

 

I wanted MD ART pipes cuz they're proven to provide excellent gains and tons of torque but they're very pricey. I may go down this road instead

 

hopefully these topspeed hfc's are a good steal on the market!

 

I'm in the same boat. I'm leaning towards the ART pipes because they do make big gains. The downside is price. If I went that route, I'd need to add a cat downstream for noise and odor issues. There are two ways I can do this.

1) Buy the MD XYZ pipe ($450) and inline cat ($250) and bolt up to the OEM midpipe.

2) Buy an aftermarket cat and weld it into the forward portion of the OEM 05 sedan midpipe. Far cheaper, but it seems like everytime I have someone do exhaust fab work, they can never quite get it right and they jack up pipe to chassis clearance.

I'm still a bit resistant to HFCs because there are lots of reports of the aftermarket cat bricks loosening up and possibly breaking up and getting sucked back into the engine.

 

^ Getting sucked back into the engine? Say whaaaa?

 

getting sucked into the engine? hmmm interesting...

not a good thing for an car related OCD person to hear.

 

A lot of people on this forum have been running HFC's for years and I haven't really heard any issues like that. I'm not too worried

 

thats what happens to 02-03 QR25DE's, they sucked in the precat. I just expect to get a new engine when i buy a post 2002 nissan

 

^What?

 

most of the 02-03 sentra SE-Rs sucked in their precats and needed new motors, including mine. then i got my g and it needed one too

 

Yes, there have been some HFC issues over at the my350z where the cat brick became seperated in the housing. The brick then began to break up and the cat pieces where either blown into the downstream resonator and muffler and/or the smaller particles were sucked back up into the engine. How does the engine suck something into on the exhaust side? The moment you release the throttle after going wide open throttle. A vacuum is created. When the particles get pulled into the motor, they'll destroy it. Like others have pointed out, this was a problem on stock QR25s for some time.

IMO, the issue, though rare, is caused by excessively high exhaust temps and a cat brick that can't handle the temps in the long term. The high exhaust are probably related to poor tuning and consistently lean air/fuel ratios. The OEM cats don't seem to have a problem because they're very large and may be able to disapate the heat.

 

Ok... so do they rattle before chunks start flying lose? If so, then you know the moment it starts rattling, do something about it.

 

From what I understand, yes, they start to rattle. The problem is HFCs typically create a metallic ringing under load which is often confused with a loose or broken exhaust part.

Let me just add that having cat debris sucked back into the engine is a rare occurance, but it can happen.

 

That's a scary thought. I was thinking since it has to do with temp, maybe wrapping HFC and other exhaust parts will help prevent this from happening. Besides, exhaust wrap is pretty cheap, nothing to lose.

 

the exhaust temp comes from the inside of the pipe so I don't see how wrapping it would help

anyone know which brands are prone to breaking apart?

as for the rattling, my sentra's cat started rattling a good while before it started a quart every 200 miles..lol