eBay resonated test pipe...
 

This MOAB Miata has a straight test pipe in place of a cat at the moment....and it's stupid loud. The combination of the Whipplecharger, the RB header, the straight test pipe, and the FM exhaust is head-splitting for me.

The car is for sale but whether I keep it for a while or sell it soon, I'd rather cut the noise down for my own use or to not drive away prospective buyers with the stupid noise.

I was going to remove the test pipe and take it to a muffler shop to weld in a resonator, but then I searched eBay and found stuff like this:

Mazda Miata MX5 1.8L 94-97 Catless Pipe Pipes Test Pipe Resonated De-Cat

I figure that's about as much as I'd spend at a muffler shop, and this way I'd give the buyer the choice of swapping in one or the other.

Anyone tried one of these? For $75 is it worth a shot, or should I just head off to the muffler shop?

add a real cat and it will tone down the rasp a little, but the combo of a header + open exhaust = annoyingly loud awful terrible exhaust noise.

i cant imagine what it must be like with the SC whine in there as well.

I had a borla exhaust, then added a header. It was so loud, the only option was to turbo the car.

It's not so much the SC whine (which is there) as it is the mostly open exhaust with all the additional exhaust volume.

Would a cat really be that much better than the resonated pipe? It'd be twice the cost. I know this exhaust setup will never be OEM-quiet, I just wanted something that doesn't induce headaches.

I dont think either are really going to help you. You need a the biggest muffler you can find. and then add two. and install baffles. and stuff it with potatos.

I've had great luck with Ebay resonated testpipes. I ran one on my supercharged S2000 and my previous turbo Miata that was straight piped. In both instances it reduced overall noise, but more significantly elimnated the annoying raspy sound. Granted the turbo in itself muffles sound a good bit, but the resonator alone took my miata from completely unbearable to being streetable. It won't do as much as a good muffler, but it will certainly help.

Cool! Thanks for the info. Does the one I linked to look basically like the same product (I know, how different could a resonated pipe look)?

Hmm. Amazon has the Magnaflow direct-fit catalytic converter for $115 shipped.

Worth the extra $40?

You probably want to find out if they last long. The thing about cheap resonators (and straight through) mufflers, is that they get louder over time.

Ordered the Magnaflow 23696 catalytic converter. For the different in cash, I figured it was worth it.

A word of caution about the gaskets that come with these and other chinese exhaust parts.

I can't speak for every chinese gasket but I have an ebay test pipe very similar to this one and the gaskets that came with it are perforated metal with a cream/off-white core. The core of the gasket is roughly 80% asbestos(chrysotile only.) I know this because I actually worked at a lab that did testing for asbestos and I tested the material myself both by polarized light microscope and transmission electron microscope.
I also have a chinese T3/T4 that came with a black oil drain gasket that contains roughly 5% asbestos.

By itself it's not a big deal if the gasket isn't damaged or abraded. But if you use a grinder, cut-off wheel, or a 3M gasket remover disc on one of these gaskets it can put a substantial amount of fibers in the air that will stay in the air for a long time.

Additionally, even though I have not personally tested them, I suspect other Chinese products such as brakes and clutches may contain asbestos so use caution if you run them on your car(don't use compressed air to clean off brake and clutch dust, no sanding or grinding.) Again no proof of it, but please use caution.


Cliff's notes:
Some Chinese gaskets contain asbestos, please use caution.