1998 Cat-in-the-Manifold LX to EX header and exhaust

[Mehcanic79]

1998 Sedan LX
Generation: 6th
Chassis Code: EJ6
Engine Code: D16Y7
Engine Specs: 1.6L 16V SOHC, 106hp @ 6200 RPM
Cat-in-the-Manifold LX and I don't necessarily care the PUN!

I'm looking for drivability, not ALL-OUT performance. I've installed Pace Setter Header 6-2-1 and Flowmaster 40 Series muffler on my 91 Jeep Wrangler 4.0L 5 Speed. It made a world of difference in torque. 5th gear @ 30 mph and smooth! Less shifting, more balanced motor.
Naturally the choice is new exhaust for my daily driver 98 civic LX.

PART 1: HEADERS/Exhaust Manifold
I've purchased Edelbrock 4-2-1 2 piece headers (the headers are obviously for 92-00 civic EX)
Header Material: T-304 stainless steel
Header Finish: Polished
Header Style: Shorty
Primary Tube Diameter (in): 1 5/8 in.
Collector Attachment: Stock flange
Collector Diameter (in): 2.500 in.
Tuned: No
Primary Tube Gauge: 16-gauge
Flange Style: Standard
Flange Thickness (in): 3/8 in.
Bolts/Studs Included: Yes
Gaskets Included: Yes
Reducers Included: No
Y-Pipe Included: Yes
Headers, 4-2-1, 2-Piece, Stainless Steel, Polished, Honda, Civic, 1.5/1.6L, L4, Kit

PART 2: Cat/mid pipe
a: *Could be my stock LX mid pipe if it bolts up
b: Could be an EX catalytic converter (which would require a new EX mid pipe and exhaust hangers)
c: Could be a test pipe (which would also require a new EX mid pipe) but why not just use the stock LX mid pipe instead?
(*= ideal set up)

PART 3: Tail pipe/Muffler
(NOTE: the LX and EX use the same part number muffler/tail pipe 35119.
a: *use my stock Tail pipe / Muffler
b: use the axle-back Flowmaster muffler set up
(*= ideal set up)


NECESSARY MENTIONABLES:
1. I will need to extend both O2 sensors. (I will have one in the header. and EITHER one in the EX cat or I will have to weld an O2 bung and use the doubled-up Spark Plug defoulers in to the stock mid-pipe)
2. I will need to reset the computer by disconnecting the battery

LX

EX


I am hoping I can just install the header and hook it up to my LX mid pipe, Weld an O2 bung in the LX mid pipe and use two Spark Plug Defoulers to remove the O2 sensor from the direct stream. Is this possible? If not, I'm debating if custom exhaust work will be cheaper than shifting EVERYTHING to an EX style exhaust system.
So what are your intelligent thoughts? I know there are many posts about this, but nothing clean, straight and clear. I hope I've been thorough enough with this post.

 

[cgpEJ6]

my car never had an exhaust that exited the drivers side...

 

[GreenSpeed503]

i think your diagram is wrong. any 6th gen civic has the exhaust to the right. but yeah you can do that then get the axle back piping and cut off the exhaust then weld on your flowmaster. oh yeah be sure to reuse or get a new donut o-ring gasket the gasket is like 14 buck from honda and if it doesn't fit then go to a muffler shop and they'll find the right one that fits. downfall would only be the small stock exhaust piping but its also more quiet. usless you dont care how loud it is.

 

[Mehcanic79]

Thanks

my car never had an exhaust that exited the drivers side...

You're right, I was just looking at the diagrams.

The diagrams aren't necessarily wrong they just arranged everything different for some reason and that's what confused me. I downloaded from some auto website that catalogs all their parts in a different format than most.
The small exhaust piping will just help the torque and lower-RPM drivability so I do not really care if I change it.



Being that both exhaust systems use the same axle back piping I shouldn't have to cut anything since it's only the MID PIPE and further up stream that's different.

Thanks for your input. I appreciate it.

 

[Mehcanic79]

installed

I’ve finally rid my self of the pesky cat-in-the-manifold set up.

I installed the Edelbrock headers this weekend.
1. I had an o2 bung welded on the stock LX mid pipe. I then had to cut the pipe on either side of the o2 bung so I could position the o2 sensor properly. (I ended up using crappy flex pipe for time/ease constraints and it’s obviously temporary)
2. I used the double spark plug defouler trick for the 2nd o2 sensor. It is working so far, no CEL.
3. I rewired/soldered both four (4) wire o2 sensors.

Special Notes:
• The stock LX intermediate piping OD is 1.75" and the headers bolted right up to it.
• The car makes a minor rasping exhaust note at about 2700~3100 RPM in 1st-3rd gear only. I'm guessing it is due to the "flex" piping. a solid union would have been ideal, but the local auto parts places left me hanging.

Over-all:
the headers are a great improvement, The motor idles smoother, more power and drivability. Not as much low-end torq as I thought I would gain, but I can live with it. (that’s probably due to the 1.625” pipe to 2.5” collector vs. other headers that are 1.5” or less and 2.25” or less collector size) more power in the mid to high RPM range.
I will upgrade to a complete EX exhaust in the future and hopefully a bit more power will come of it and the rasping sound will diminish.

Since the mid pipe was removed, I also installed the B&M short throw shifter with energy suspension bushings. This shifting is very positive and short. Better than expected. Along with the headers smoothing the motor, the stick doesn’t shake any more, it’s like a hum now.

Thanks for everyone’s tips and advice.

 

[Szady]

Your getting that raspy ness around 3K RPM because your running w/no cat converter. When you pull up to a stop sign/light, your car smells like ass for a minute. I have the same problem. Just get a cat welded on somewhere, and that raspy-ness will be gone. Im running no cat, for the same reason you are. I have a LX, and have a Megan 4-2-1 2 pc header, but Im gonna get a cat welded into my piping before inspection rolls around, so I can pass.

 

[Mehcanic79]

I think I will go with a magnaflow catalytic converter from summit racing for $149.00 (I would assume that all stock replacement cats will have a position for the 2nd O2 sensor?)

as for cat-back I'm debating just to get the dynomax DNX mid-pipe and retain my stock muffler ($116.00)
or
get a Tanabe Medalion Touring cat-back (about $500)
or
greddy SP2 cat-back (about $500)

I don't want anything that is annoying and quieter the better. this is a commuter/freeway car.
Any other good quiet exhausts and/or reputable places to purchase from?

Thanks

 

[Mehcanic79]

finishing up

I can’t believe sans-cat that the exhaust would sound raspy like that with the stock resonator and muffler still in place. It’s sounds more like something is loose in the 3000 rpm frequency. This is why I thought it may be the flex piping that I used. I will have to research this more. I put headers on a Jeep wrangler, straight pipe to a 40 series Flowmaster muffler and it sounded really nice with no rasp though it was bit loud at freeway speeds (hummed loud anyhow).

However, I think I will go with magnaflow catalytic converter from summit racing ($150) for direct fit.

For the remainder of the exhaust I’m debating:
I want to keep the noise level as low as possible since I mainly drive this car freeway/commuting.

Add the Dynomax DNX mid pipe (approx. $120) with the new cat and keep the stock muffler/tail pipe section
Add a Tanabe Medallion Touring cat back (approx. $500) with the new cat
Add a Greddy cat-back SP2 (approx. $500) with the new cat

Any other nice quiet exhausts? Reputable places to purchase?

Thanks for the input.

 

[Mehcanic79]

Your getting that raspy ness around 3K RPM because your running w/no cat converter. When you pull up to a stop sign/light, your car smells like ass for a minute. I have the same problem. Just get a cat welded on somewhere, and that raspy-ness will be gone. Im running no cat, for the same reason you are. I have a LX, and have a Megan 4-2-1 2 pc header, but Im gonna get a cat welded into my piping before inspection rolls around, so I can pass.

I can’t believe sans-cat that the exhaust would sound raspy like that with the stock resonator and muffler still in place. It’s sounds more like something is loose in the 3000 rpm frequency. This is why I thought it may be the flex piping that I used. I will have to research this more. I put headers on a Jeep wrangler, straight pipe to a 40 series Flowmaster muffler and it sounded really nice with no rasp though it was bit loud at freeway speeds (hummed loud anyhow).

However, I think I will go with magnaflow catalytic converter from summit racing ($150) for direct fit.

For the remainder of the exhaust I’m debating:
I want to keep the noise level as low as possible since I mainly drive this car freeway/commuting.

Add the Dynomax DNX mid pipe (approx. $120) with the new cat and keep the stock muffler/tail pipe section
Add a Tanabe Medallion Touring cat back (approx. $500) with the new cat
Add a Greddy cat-back SP2 (approx. $500) with the new cat

Any other nice quiet exhausts? Reputable places to purchase?

Thanks for the input.

 

[Mehcanic79]

Your getting that raspy ness around 3K RPM because your running w/no cat converter. When you pull up to a stop sign/light, your car smells like ass for a minute. I have the same problem. Just get a cat welded on somewhere, and that raspy-ness will be gone. Im running no cat, for the same reason you are. I have a LX, and have a Megan 4-2-1 2 pc header, but Im gonna get a cat welded into my piping before inspection rolls around, so I can pass.

I can’t believe sans-cat that the exhaust would sound raspy like that with the stock resonator and muffler still in place. It’s sounds more like something is loose in the 3000 rpm frequency. This is why I thought it may be the flex piping that I used. I will have to research this more. I put headers on a Jeep wrangler, straight pipe to a 40 series Flowmaster muffler and it sounded really nice with no rasp though it was bit loud at freeway speeds (hummed loud anyhow).

However, I think I will go with magnaflow catalytic converter from summit racing ($150) for direct fit.

For the remainder of the exhaust I’m debating:
I want to keep the noise level as low as possible since I mainly drive this car freeway/commuting.

Add the Dynomax DNX mid pipe (approx. $120) with the new cat and keep the stock muffler/tail pipe section
Add a Tanabe Medallion Touring cat back (approx. $500) with the new cat
Add a Greddy cat-back SP2 (approx. $500) with the new cat

Any other nice quiet exhausts? Reputable places to purchase?

Thanks for the input.q

 

[Mehcanic79]

Your getting that raspy ness around 3K RPM because your running w/no cat converter. When you pull up to a stop sign/light, your car smells like ass for a minute. I have the same problem. Just get a cat welded on somewhere, and that raspy-ness will be gone. Im running no cat, for the same reason you are. I have a LX, and have a Megan 4-2-1 2 pc header, but Im gonna get a cat welded into my piping before inspection rolls around, so I can pass.

I can’t believe sans-cat that the exhaust would sound raspy like that with the stock resonator and muffler still in place. It’s sounds more like something is loose in the 2700~3000 rpm frequency range. This is why I thought it may be the flex piping that I used. I will have to research this more. I see other people are having this same issue even running cats. Sounds like you need to use proper spring bolts between cat and header else the seal won’t fit properly and you’ll get that nasty noise.

However, I think I will go with magnaflow catalytic converter from summit racing ($150) for direct fit.

For the remainder of the exhaust I’m debating:
I want to keep the noise level as low as possible since I mainly drive this car freeway/commuting.

Add the Dynomax DNX mid pipe (approx. $120) with the new cat and keep the stock muffler/tail pipe section (perhaps later add a flowmaster axle back set up approx. $190)
Add a Tanabe Medallion Touring cat back (approx. $500) with the new cat
Add a Greddy cat-back SP2 (approx. $500) with the new cat

Any other nice quiet exhausts? Reputable places to purchase?

Thanks for the input.

 

[Mehcanic79]

testing

Testing this space. I keep trying to post but for some reason it hasn't been letting me.

Testing this space.

Will update Soon!