Raspy sounding...high flow cat>Test Pipe?

[barch88]

My car is sounding raspy again. Not nearly as bad as when I had my muffler delete, but since I've added the header and catless downpipe she's buzzy again. I have the ZZP muffler already, so I'm guessing the only thing I can do to fix this would be a high flow cat then? How much would this decrease performance, if any?

Thank you,

Mike.

 

[$ub$onic]

The cat would help A little but it will always have A little rasp to it

 

[mitdr774]

In my pursuit of exhaust "perfection" I have tried many combinations. I have finally given up for the most part. My current set up is BNR 4-1 header, ZZP high flow cat, Flowmaster HPII resonator (12512400), Flowmaster HPII muffler (12518400), Magnaflow muffler (11376), and finally a resonated exhaust tip. For the most part it is quiet enough, decent tone at idle, cruise, and light to moderate throttle input, low levels of interior drone, and does not piss off the neighbors. Unfortunately if you get on it the exhaust sounds tinny and does get some rasp. This is going to be hard to get rid of due the nature of being a 4 cylinder with a decently flowing exhaust system. If I put the stock maniverter back in all the rasp will be gone and I could ditch the Magnaflow muffler.

 

[Preloader]

Believe it or not exhaust does "break in".

When I first installed my DDMW cat-back, I was upset because it had a farty rasp. It calmed down and went away after about a thousand miles.

 

[mitdr774]

High flowing N/A 4 cylinder exhaust is very hard to make sound good. So far my favorite sounding setup has actually been the stock maniverter and second cat, with the SLP cat back. I suspect a small turbo would solve all my exhaust sound issues.

 

[rdss]

Like mitdr said, adding a high flow cat and resonator into the mix will reduce the rasp a lot. Preload is correct as well, the packing "breaks in" with the process of heat cycling it eventually giving you a different tone and the older it gets it will continue to change. Cheap packing will also cause an exhaust to go from something you love to something you can't tolerate. I would recommend going with ZZP's high flow cat test pipe and a 14" to 18" long by 4-5" diameter resonator of your choice, which Magnaflow has always been mine.

 

[barch88]

Thank you much for all of your replies. I find myself doing trial and errors now too .

I'll try a resonator first, since that'll be the cheaper option, then if it's still too loud I'll go with a high flow cat. My muffler system is well broken in, besides the header and DP, if that matters.

 

[mitdr774]

This was a previous attempt when i didnt have a cat in the car. That is the HPII resonator, 22" Mafnaflow, and a Thrush super turbo muffler. It had the same issues I have right now. Next year I may look into fitting a muffler in a manner to allow a side exit without going over the axle.

 

[barch88]

So we've added a glasspack/resonator. It helped a bit, doesn't sound as loud and raspy but still has a small rasp to it. It's tolerable now. I think adding a high-flow cat would fix the issue entirely but I'm pretty happy with the sound now.

 

[Black Turbo LTZ]

So we've added a glasspack/resonator. It helped a bit, doesn't sound as loud and raspy but still has a small rasp to it. It's tolerable now. I think adding a high-flow cat would fix the issue entirely but I'm pretty happy with the sound now.

Sucks I didn't read your thread earlier, I solved mine with the "dual chambered" resonator, I was offered the glasspack but opted for the dual chamber since it made a big difference sound wise...my sound is smooth as it gets up in the RPMS.

 

[mitdr774]

Sucks I didn't read your thread earlier, I solved mine with the "dual chambered" resonator, I was offered the glasspack but opted for the dual chamber since it made a big difference sound wise...my sound is smooth as it gets up in the RPMS.

Huge difference in the needs of an exhaust system to control sounds when comparing a turbo to N/A car. What works on your car may not work on a 1.8.

 

[ChrisJ]

Just curious,
Am I right in assuming the raspy sound is mainly caused by valve and ignition timing?

My experience has been more retarded ignition timing gets a chuggy sound to it while valve timing seems to get more rough sounding as overlap increases?

That sounds backwards but my point was running more advanced ignition timing = less chuggy and more rough combined with the valve timing = raspy? So even though raspy sounds like crap, it really sounds like power at higher rpms.


I notice the ignition timing's effect on sound a lot when driving the "a" because its manually controlled.