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Is there any benefit to installing a S4 exhaust manifold & front pipe on a S2/S3 Sipder? The other question is will the S2/S3 single wire O2 sensor fit the S4 front pipe without modifications? My front pipe should be replaced. I may be able to get a manifold & a solid front pipe for a S4 for a bargain. If it'll fit I just may be tempted to do the swap. I can get a new Magnaflow front pipe for the S2/S3 for $225.00. But I figured WTH if I'm spending the money anyway why not go for the gold. The S4 ex manifold looks sportier. BTW I dislike headers on a daily driver.
 

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Ok, I gotta ask... Why do you dislike a header on a daily driver? I switched from a S3 manifold, which cracked, to the IAP header and really like it not that I resolved some of the fit issues..



Ed
 

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Discussion Starter #3
Ok, I gotta ask... Why do you dislike a header on a daily driver? I switched from a S3 manifold, which cracked, to the IAP header and really like it not that I resolved some of the fit issues..



Ed
My experience with headers is that they require more maintenance that I want to dedicate to tightening bolts and chasing exhaust leaks. Now in a race car I don't mind the fiddling cuz I'm usually there anyway but for a street cruiser I want it to be quiet and not be bogged down with chasing the little things over & over.

The last header that I had on a street car was on my SRL311 Datsun 2000 Roadster. I finally fabricated and piece of stainless steel flex steam hose between the collector and the front pipe to keep the header from constantly cracking & coming loose. That and for some reason headers just don't fit up to the head very well.
 

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Interesting... I had an odd situation with the IAP header where it was hitting my steering box, otherwise it hasn't leaked and really does make a difference in the cars ability to rev. The S3 stock manifold and down pipe are pretty restrictive.


Ed
 

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Interesting... I had an odd situation with the IAP header where it was hitting my steering box, otherwise it hasn't leaked and really does make a difference in the cars ability to rev. The S3 stock manifold and down pipe are pretty restrictive.


Ed

I agree that the s2/s3 manifold & front pipe looks pretty constipated. It looks like Alfa did a better job on the S4 manifold & pipe if they will fit my chassis.
 

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I thought the old 2 part cast S2 type was thought to be the one of the best. even outperforming some of the tube headers.
 

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That is what I've heard about the old S2 two piece manifolds as well. I did also hear that for the S4 they moved back to a a configuration very similar to the S2 setup. The only problem I think you'll have is bolting it up to the cat (assuming your have the stock one) although it sounds like you you just have a pipe in place of that? Anyway, it won't just be a bolt on as far as I know but just simple mods for an exhaust shop. As far as the O2 sensor, from what I've seen they all seem to be the same size and thread.

Kevin
 

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BIG difference! I've got the old 2-piece S2 exhaust manifold (from a '74 Spider) on my 87 Spider, along with the rest of a '74 system all the way back. Only had to weld in a bung for the generic Bosch O2 sensor. I would never again drive my '87 Spider any other way. Of course, no catalytic convertor, but no inspections here in FL, either. Even if there were inspections, I'd have two systems and swap back the OEM just for inspections. Like I said, BIG difference!. Now that I've got the "new" '92 Spider, it looks like that manifold is the same as the old S2, except it has studs (rather than bolts) to fasten the downpipes. The older S2 manifold is likely cheaper/easier to find. FWIW, not only do I think headers are a useless PITA on a street car, I think the original 2-piece manifolds and downpipes offer the best all-around performance.
 

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I have been trying to decide between headers and older S2 manifolds. I rather use the older manifolds but they don't have the 02 bunge and the headers do. Is there anyway to get the o2 sensor connecter without welding? If I took the manifolds to a welding shop, is there a bunge adapter you can buy or does it have to be fabricated? I tend to agree with Geezer, I rather use manifolds then headers if I can.
 

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Ive. done it both ways. The grad. has an old Shankle header which has the o2 sensor bung included, no cat, stock center muffler, Ansa dual tip rear muffler. Veloce has 1750 cast headers, modified cat section to fit headers(cut off the pipes and flanges & replace with 1750 down pipes), the remainder stock for now. Shankles PITA to install since they seem to be larger and are hard to get past steering box. Otherwise faifly straight forward. The gra. sounds great. Havent gotten the Veloce out on the road yet since it needed a lot of other things to make it a real driver.
 

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I have been trying to decide between headers and older S2 manifolds. I rather use the older manifolds but they don't have the 02 bunge and the headers do. Is there anyway to get the o2 sensor connecter without welding? If I took the manifolds to a welding shop, is there a bunge adapter you can buy or does it have to be fabricated? I tend to agree with Geezer, I rather use manifolds then headers if I can.
If you are planning on using a cat, most of them have a hole to screw the O2 sensor into. The newer style high flow cats are supposedly pretty good and a lot cheaper than the stock type.

Kevin
 

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Discussion Starter #14
Hadn't thought about the 2 piece S2 manifolds. Does anybody know if the 2 piece S2 and 1 piece S4 terminate in about the same place? The pics make the look very much alike.
 

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I have a '91 S4 and my mother has a '84 w/ S2 exhaust manifold. Well, I cannot compare them side by side (the '84 is on the other side of the Pacific Ocean) but like you said, they look pretty much identical except for the studded front pipe mounting flanges, mount for heatshield (absent on my early S4), and part number casted on them (I think the S4 ones say 01588...). I have not tried this myself, but I would not be surprised if they are interchangeable.

On my mother's '84, we have the S2 manifolds and the S2 front pipe (w/ a Toyota cat) and boy, what a difference!! I am pretty sure that you can get similar performance gain w/ S4 manifolds and S4 front pipe as long as you have a good intact cat. The only thing you may have to modify is the connection to the center pipe. Since the S4 uses different center pipe, you may have to have a local exhaust shop cut & weld the old flange from your current front pipe onto the tail end of the S4 frontpipe.


Hadn't thought about the 2 piece S2 manifolds. Does anybody know if the 2 piece S2 and 1 piece S4 terminate in about the same place? The pics make the look very much alike.
 

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The series 2 is the way to go. You can still get a complete bolt up system that looks stock from front to back. By the way the front can on the system looks just like a convertor. All you need to do is weld a fitting in the front pipe for your O2 sensor.

The series 4 manifold will not bolt to anything but the stock set-up.
 

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FWIW, I bought an O2 sensor bung for ~$5 at NAPA. I used my Dremel and a little cutting wheel to cut the appropriate sized hole in one of the stock '74 downpipes, and then took the pipe and bung to a local muffler shop. For another $15 I had the bung welded in, and I was set to go. Just be careful in choosing where to put the bung, as there may be clearance issues with the sensor and frame rails. There are generic Bosch O2 sensors (both 1- and 3-wire that can be bought for ~$35). I think it's been about 3 years and ~25,000 miles since I did this mod to my '87, and there have been no issues of any kind. If I recall, the '74 manifolds wer ~$50 shipped (eBay), the front/middle section of the exhaust (original one piece CISAM, from IAP) was ~$180, and the rear (also origonal CISAM, downturned tip) was ~$80. Best $350 I've ever spent.
 

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What about the cast iron "stock" S2 manifolds that IAP sells? Anyone have experience with them? If most headers have so many problems with bolting up, maybe these stock manifolds would be a good alternative.
 
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