I have a 97 Civic HX all stock. The CEL is on because the cat has gone south (or so the codes would indicate).

My town has a fondness for salting the roads, so just about every other year I've had to replace the resonator pipe or muffler. And every time I do, I swear I'm going to get a stainless exhaust. Looks like now might be the time.

Given the need for a new cat, it looks like I have a few options:

1) Replace the entire setup with an EX style exhaust/cat
2) Replace the cat/manifold and install a stainless catback
3) Replace the cat/manifold and continue to swap out the B pipe and muffler every so often

I don't care about boosting performance but I do care about sound and emissions, mostly because the state (Mass) cares about them. I'm looking at aftermarket because the OEM parts appear to cost more than the car is worth. When going with the EX option, it looks like I need a header, but I've read conflicting info about whether any beside the DC are street legal. Any suggestions?

 

If it'll fit, personally, I'd go with the EX header/cat versus the HX (sorry, not that familiar with the HX design). The DX/LX has the cat built into the exhaust manifold, which gets expensive quickly when you have to replace it (knocks on wood daily....).

I just upgraded my exhaust to a resonated Magnaflow stainless cat-back. It bolted right up to my stock LX manifold, and has an extension section that can be simply unbolted if I decide to go with the EX manifold someday. Like you, I got it for it's stainless steel construction, plus the lifetime warranty, which totally justified the cost for me.

The sound is very deep, but not ricey-loud where it'd raise too many eyebrows. I drive past police all the time and have never gotten a second look. But if you give it some revs, it'll respond nicely with a good, mature sound.

I ended up with the 2/25" tubing which fit fine under the car with some minor tweaks to the exhaust hangers. The only thing I don't like is the comically massive 4" exhaust tip.

 

The HX is a VTEC engine with the same manifold as the DX/LX, giving it less power but better gas mileage than the EX.

I'm also looking at the Magnaflow stainless cat-back - either the 15642 if I stick with the HX manifold/cat combo or the 15646 with the 22628 cat if I switch to an EX header. Magnaflow seems to be one of the quieter options and I don't need to give the MSP any additional reasons to pull me over.

My inclination is to switch to an EX exhaust, but I'm unsure about which header will make it more likely that I'll pass my emissions test. Nearly all of them that I can find say "off-road use only" with the exception of the DC Sports.

 

Do you live in California? If so, you are forced to buy something C.A.R.B. approved like the DC sports unit. If not, as long as you have a OEM spec cat converter, you should have no problems.

The vtec in the HX is not like the vtec EX. HX runs on three valves, until it hits vtec where it then runs off of all 4 valves. Saves gas.

EX runs on 4 valves all the time and vtec allows the intake valves to bring in more air etc etc etc

 

No, I live in MA which is almost as bad. The law says replacement exhaust can't be louder or more polluting than OEM.

Edit: Just did some research, and it looks like the cams and tranny are different, which makes sense. Also, it looks like one of the two intake valves in each cylinder opens partially at low RPM to allow for a leaner fuel mixture.

 

I should also say, while I don't live in Cali, the car has a California emissions label. Not planning on moving there anytime soon, but I wonder how that impacts the Mass law and whether I need a CARB cat and header even living on the other side of the country.

 

One last thing...

It appears the pre-cat O2 sensor has five wires rather than four. Does anyone know of an extension cable for it? The only cables I've found are four-wire. I'd rather not make one up myself if I don't have to.

Apparently this O2 sensor also has the side-benefit of being nearly three times as expensive as standard - hopefully it will come out without much fuss, although with 196k on it, I kinda doubt it.

 

Replaced exhaust manifold with ME stainless header, and magnaflow cat and cat back. While the exhaust sounds okay, my local mechanic thinks it will be too loud to pass inspection. But I need to fix another problem first...

 

Well, got it all put back together and after solving some other problems with the engine... if failed inspection.

Two things I learned:

1) Massachusetts doesn't like any modified exhaust, particularly if it sounds louder than the OEM.

2) Massachusetts adopted the California CARB laws last year so all replacement emissions parts need to be CARB listed.

Looks like I'll be putting my Magnaflow 15646 cat back up for sale. Is $250 + shipping too much to ask? It's only got about 100 miles on it and I see it new on Amazon for $490.

 

You GOT to be kidding me. That's insane. I would argue about it especially if there was no formal document about it once the laws were accepted.

$250 is definitely a good price.