So the other day I installed an exhaust, a HKS hi power cat back exhaust. Anyways at first it sounded really nice and aggressive and now it sounds a little raspy. Any idea why ? It mostly does it in second gear around 3000 rpm

 

Authentic hks or a replica hks? If it's a replica these guys will eat you alive

 

its authentic

 

your supposed to install. run the car let the exhaust heat up and then re tighten the bolts. heat expands when metal's get hot which may cuase some bolts to not be as tight. which may cause raspy noises.

go under your car and check for leaks.

 

I'm having the same issue, with a nismo exhaust though. Sounds like a honda. No exhaust leaks and data-logging comes back with perfection.

Leaks will affect the rasp, check for soot.

Are you burning oil? Oil can contaminate the muffler packings, ruining the muffler. I'm suspecting that's what happened in my situation.

Burrs and misaligned gaskets will also cause rasp/farts.

 

Packing is warn out or muffler bearing needs greased.

 

Not sure if serious on muffler bearing lol

 

you didnt know mufflers have bearings?

 

Don't forget to change your blinker fluid as well.

 

Haha little slow sometimes

 

I've had a fair share of exhausts that have changed note slightly once they get a good coating of carbon on them (the black stuff you see in the tip) and as they "wear in." it's possible that it's just the nature of your particular exhaust system. Still, like the others said, check for leaks and tightness first. If you scrape, like I do, check for cracks around the hangers, I've had that happen before.

 

Like everyone else would say... Buy a motordyne

 

I'm good with my invida.gemini With testpipe. deep rumble, mellow tone, zero rasp, mild drone.

 

I'll second invidia gemeni with my FI resonated test pipes.. incredible sound, nos rasp or drone.

 

hey have you had this experience with a motordyne and art pipe setup? I have both and the exhaust note changed after about a thousand miles went from raspy above 4k to an even deep vq sound. normal?

 

Every muffler (with packing inside) will change in sound over time as soot gets in the packing and it will also change composition from heat.