Thanks a lot. You've convinced me. Magnaflows it is. I'm going to get under the car and see the longest size I can put in there. Since I have HFC's and not test-pipes I figured one pair of the greatest length possible should work nicely.

One more Q, what diameter is the body of your resonators (where the packing/baffling resides)? I found 4", 5", and 6" - I want to get the largest size possible but need to make sure it fits in there.

-B

 

4" round is what you want.

 

Sweet, just got these 14" resonators today for about $75 each:

http://www.magnaflow.com/02product/s...ne=main&id=654

I'm having them welded in next Thursday to replace the dinky Stillen resonators (which are only like 8" in length). I'll let you know how I like the results.

Thanks a lot for the help.

-B

 

Cool. Just make sure when they weld them in that they leave enough room for more if you ever want to get quieter. I got 2 18" back to back and it is quiet, smooth POWER.

 

Cool, thanks.

I barely fit these 14" resonators into the mid-section of the piping (they're welding it into the red circle area of the picture below), so I won't have to worry about them leaving room there - it's already stuffed. I don't think I could put on more resonators - just check out the picture below and see for yourself. There aren't many straight runs in the Stillen cat-back system for the coupe, and the few small straight runs I see have a stabilizing bar or other hardware obstructing a bit so it'd be tough if not impossible to stick a wide-body resonator in there.

http://70.32.21.62:2006/Stillen_Exha...r_Replaced.htm

I'll see how it sounds after this upgrade. If I don't like it, I'll consider trying to add more (if it's even possible). Who did your welding?

Thanks,
B

 

So, the new resonators are in and here are the results:

1. That annoying "rattle" at certain RPM's is still there but not as noticeable.
2. The drone and overall exhaust noise increased (which may explain why the "rattle" is less pronounced).

Kind of a bummer but I guess it could be worse. For what it's worth, the car feels more powerful now. But that's probably in my head. Guess I'll start thinking about that twin turbo kit to bring the noise down a bit!

-B

 

Okay, so I've driven the car a bit more today and here are my second thoughts.

The "rattle" I used to hear is gone. But there is that slight noise around 3000 RPM for a split second that sounds somewhat like a rattle. I've read that this is a normal sound for our engines once you open up the exhaust flow. Still, there used to be a loud rattle around that same range that was definitely some loose metal - most likely the faulty Stillen resonator - and it lasted for almost a full second. That rattle is gone.

Yes, the car got louder but it sounds more like a V-8 now. Or as close to a V-8 that our cars can sound. So the exhaust note got deeper only. It used to sound somewhat high-pitched with the Stillen resonators - more "ricey" IMO. Now it sounds more like a muscle car.

I still prefer the smooth OEM/Stillen cat-back-only Euro sound but I have to live with the choices I've made, there's no turning back. I'm to addicted to the power now!

-B

 

Okay, so the car sounds even better today. I wonder if the resonators needed a break-in period, similar to cats? It's still deep and aggressive but not quite as loud as yesterday. And definitely less drone and than before the new resonators were put on.

Long story short - I'm very pleased with the outcome of replacing the "Stillen" resonators with the Magnaflows.

 

I noticed the same thing. It will tone down a bit more over time, but the 3-3.3K "Rasp" will be there with testpipes or HFC. All you can do is minimize it. Another thing that really helps is to thermal wrap the tubing after the actual catalyst section of the HFC and then all the way to the X-pipe. Wrap it really tight to dampen the ringing/resonance of the pipe as the gas flows. Kind of time consuming to do, but it made a big difference on mine.

 

Thermal wrap sounds interesting...does that prevent the heat from escaping off those parts of the cats/y-pipe? Meaning, is there any risk to the cats or exhuast pipes from excessive heat if you lock it in like that?

And how does thermal wrap work to reduce sound? Just wondering what sounds reducing properties it has...

And which should I buy?

Thanks,
B

 

Any autoparts store that sells some level of aftermarket performance should have header wrap. I used the Thermotec 2" wide. No issues with heat buildup, but don't wrap the actual (larger dia.) catalyst section as it needs to dissipate much more than the regular piping sections.

The rasp that you're hearing is resonance "ringing" of the tubing from the exhaust pulses. Stillen uses a very hard, high grade stainless that can ring like a bell or tuning fork at certain RPM. What you are doing by wrapping it, is damping the amplitude of the resonance. Think what would happen if you wrapped a chuch bell with a blanket. It wouldn't ring as loud would it? Same thing here and with the rubberized speaker damping in doors. Just make sure it is wrapped tight or all you are doing is muffling it, not actually damping.

 

Thanks again for all the info. I'll give it a shot and let you know how I like the results.

-B

 

Hey Ballisticus,

Two more questions before I go for the thermal wrap:

1. How much will I need to cover half the cats down to the Y-pipe joint?
2. When wrapping, should I just overlap half of the 2" width each time around?

I was considering spraying some silver 1200 degree paint over the thermal wrap when it's fully applied for a slightly better look. I wonder if that would have any effect on the resonance damping effect...? Maybe I'm being too **** but I can't help it when it comes to my G.

Thanks,
B

 

I would get 2 50' rolls. You can always bring the other one back if you don't use it. You will also need some 2 1/4 - 2 3/4 hose clamps to hold each end from unraveling.

Overlap 1" is what I did and it worked fine. Remember to really pull it tight as you wrap it.

I don't know about the 1200 paint. You really cant see the pipes at all unless you climb down there and look. And I think the exhaust is actually closer to 1800-2000 degrees under full load, especially near the cats. The wrap is good to those temps, but a pigmented paint could be a fire hazard. Not recommended.

 

Thanks, sounds good. I already bought one roll of 50' wrap and will pick up another. I also got a silicone sealant (designed for this application) to protect the wrap (recommended by manufacturer and auto parts store).

I'll hold off on the silver high-temp paint.

I should be wrapping the pipes next week some time, when it warms up a bit (it's 18 degrees out right now). I'll let you know how it goes.

Thanks for everything,
B