Noticed this rattling this morning. the magnaflow cats have about 300 miles on them. They have always been louder than stock from the first crank up, but the rattle when I rev it at park is new. I don't believe I heard it while moving, or least I couldn't. acceleration is fine with no hang ups.

What say y'all? should I try to get them warrantied or keep looking for the source elsewhere? all bolts are tight. I can check them again, but I tightened them a few days after I installed it.

no codes on the dash. no pending codes. brand new O2s, muffler, tailpipe and full top end reseal from the heads up in the last 1,000 miles. inline thermostat mod. I did just replace my power steering pump the other day, so I removed the fan, AC compressor, and PAS pump bracket and it made no rattling prior. I didn't touch the exhaust system during that time though, but if it's thought to be correlated that might be helpful to know.

 

Could it be a loose heat shield ?

 

I'll check that but the heat shields are a part of the casing from what I can tell. here's a photo of what they look like. it's a bit different thank stock.

 

Louder is normal with these aftermarket converters. Does your truck have any kind of misfire? A misfire can prematurely ruin a converter. Also look for places that the exhaust or converter body may be rattling against the frame or something else. 1/4" or better gap is necessary to prevent rattle since there is some give to the engines location due to rubber motor mounts.

 

no misfires. brand new plugs, wires, and full top end reseal done two months ago at a rover specialist. I'll check for frame contact again and see what I can find. I replaced the rubber hangers about 6 months ago but they've already cracked. just got new poly ones in the mail so looks like I'll be adjusting that here all here soon.

 

I had a set..it went to both side cat rattling in just over 6 months....bought a second one...no rattle, but the fit was not on par as the first one (one mani flange at different angle than the other)!...I think the quality control is not the best...but 2 piece is nice......

as for flow, no matter which pipe you choose, the stricture in the header to downpipe is always there...

 

Check for contact or something loose. I've got eight months on my Magna Flow cats and the only rattle came from the union at the Y pipe and the muffler. It had come loose. I tightened it up and the rattle was gone. I have the full system. Manifold to to tailpipe.

 

Is there anything definitive for aftermarket cats? I might be on the cusp of needing new ones and see the aftermarket options. Reviews where I can find them appear to be hit and miss on fit and quality of the cat itself. Curious if there is a good / better / best out there.

 

my noise went away. Not quite sure what it was but that was the only Instance I heard it. The magnaflow are good. They’re louder but they are “high flow”. The truck sounds good and no codes in 500 miles whereas I was resetting my old codes every 7 miles once the cats heated up

i was also able to sell my OEM cats for $1250 to a recycler so the replacements were free plus 3 hours of my time to Install in the driveway

 

The noise was the heat shield on the muffler hanger right by where the y pipe and muffler connect. I pressed against it while it was running and the rattling stopped. Repeated to confirm.

and yes, I have a new poly hanger on the bench. This rubber one cracked in 7 months. Kinda frustrating but easy fix. Hopefully the poly lasts longer.