DSM too loud to pass inspection

I've already hit a snag with the 93 Eclipse GSX I just bought - it's too loud to pass safety inspection. Although MA does not emissions test pre-OBD2 cars, it does expect exhaust noise to be within certain limits, and also for the car to not smell like uncatalyzed gas. It passed everything else. The DSM currently has what looks like a custom 3" turbo-back exhaust with no cat. converter, going to a round Magnaflow muffler.

Here's what I'm thinking, since I don't want to shell out for a stupid-expensive Apexi or HKS kit that has the melon-shooter outlet. The 3" piping stays. From Amazon, get a Magnaflow universal catalytic converter, to quiet things down and get rid of the uncatalyzed smell:

http://www.amazon.com/Magnaflow-53009-Universal-Catalytic-Converter/dp/B000XQM36U/ref=sr_1_1?s=automotive&ie=UTF8&qid=1351017932&sr=1-1&keywords=magnaflow+53009

Also get a Dynomax VT muffler to quieten things further. Since the Dynomax is valved, it opens up at higher RPMs.

http://www.amazon.com/Dynomax-17962-VT-Muffler/dp/B0057NS1JC/ref=sr_1_2?ie=UTF8&qid=1351018171&sr=8-2&keywords=dynomax+vt

Have all this and a new tip installed at an exhaust shop.

Any other suggestions? I'd like to keep some performance but it's more imperative right now that the exhaust be quiet.

What's the dB limit?

The smell thing seems mighty subjective.

If you want it to be temporary, get a "Supertipp". It worked on my Locost. I just slip it over the exhaust tip when needed.

It still smells like gas even when warm?

Instead of a catalyst I'd just put a resonator in there......if anything it'll quiet it down and make it sound better.

Depending on how the sound test is, a 90* turndown will kill the noise also. A good idea is AS CHEAP AS POSSIBLE and remove whatever you add afterwards.

DSM's are supposed to sound like obnoxiously loud tractors (drools).

Yeah, stick a silencer in the muffler when you go there, yank it as soon as it gets home. Who cares how it runs during inspection as long as it passes.

Whatever goes in is permanent. It needs to pass yearly (if I keep it that long), I want less attention from the cops, and I could be dinged by the Lemon Law if I sell a car that fails inspection to another MA resident. Since I bought the car from NH, I don't have that to fall back on.

I just called up a local performance exhaust shop and will have them take a look. Hopefully a resonator will be all it takes...

I know that all Rally cars are required to have cats and that is all that is on most of their exhaust systems. They are not very load at all using the turbo as muffler 1 and cat as muffler 2. They all had to pass sound tech at each rally start. It would kill 2 birds with one stone and should not be too expensive.

In reply to former520:

thats mainly so they don't burn the forest down......

magnaflow spun catylitic converter instead wont do much for sound deadening but will get a car back on it which by law the car does need to have regardless of emission exempt or not. and then flowmaster super 40

yamaha wrote: In reply to former520: thats mainly so they don't burn the forest down......

Rally cars drive on the road and are thus required to have a catalytic convertor.

A spark arrestor would solve any fire problems.

In my brief experience with a DSM, a cat makes a massive difference to the noise level. Might be worth just starting with that if this is the only problem.

If you're smelling unburnt hydrocarbons, I think a closer look at the ECU mapping might be in order...

http://www.amazon.com/Flowmaster-943045-Super-Muffler-Aggressive/dp/B000QJMZ76/ref=sr_1_1?s=automotive&ie=UTF8&qid=1351025089&sr=1-1&keywords=943045 and http://www.amazon.com/Magnaflow-54959-Universal-Catalytic-Converter/dp/B000XQQPFA/ref=sr_1_1?s=automotive&ie=UTF8&qid=1351024824&sr=1-1&keywords=54959 this problems solved

former520 wrote: I know that all Rally cars are required to have cats and that is all that is on most of their exhaust systems. They are not very load at all using the turbo as muffler 1 and cat as muffler 2. They all had to pass sound tech at each rally start. It would kill 2 birds with one stone and should not be too expensive.

That's a good point. I plan on rallycrossing my DSM and the SCCA Stock and Prepared categories require a cat. converter be installed. I'll probably end up in Prepared once I replace the missing interior panels thanks to the turbo-back and strut tower bars.

I'll have just a cat installed first. If that doesn't quiet things down enough then I'll probably have the old Magnaflow muffler replaced.

Not having a cat may be the biggest problem. Most inspections don't check for noise.

Get some steel wool and a 2 1/2" long self tapping screw. Push the steel wool into the exhaust from the tip until you get to the first bend where it goes under the axle. Use a broom handle. Then run in the self tapping screw to hold in the steel wool. This will muffle the car down to "hearing a mouse fart" level.

Then run a half tank of E-85 to get rid of the raw gas smell. Warm the car up completely before taking it in and lean it out at idle with your preferred method of fuel control (gutted MAF, Apexi AFC, or DSMLink)

Boom, instant pass.

No E85 in MA or NH.