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Hello guys I need you help with choosing the exhaust system.
I have 2 options on the table:
1- Having the exhaust done at a local exhaust shop, traditional bend(steel, 2.25” outer diameter, original bends) and using original W/Z manifolds
2- Ordering the header-back kit from Summit, mandrel bent (2.5”, 409 stainless, not exact bends) and replacing the W/Z manifolds with headers.
My muffler of choice are Dynomax Super Turbos.
1974 Oldsmobile 442 455ci full restoration.
(progress in recent thread)
Option 2 is obviously more expensive but if it’s worth it I don’t mind paying for it. Many advise against headers, what do y’all think? Any opinion and advice is greatly appreciated!
I'd go with a local shop before ordering from Summit or Jegs. I have headers on my 71 98. They're the quality Hedman headers but are still a PITA. I haven't gone back to the W/Z manifolds yet though. 🤔
You can get the kit and what they call a box of bends. This will allow any shop that is worth a damn hook the 2.5" mandrel bent system to the oem manifolds. and not need to run headers.
Is it worth it. depends on how you use the car, crimped oem style bends don't flow all that well and a 2.25 pipe with crimp bends is under 2" at the bends.
The 2.5 kit and box of bends will be 2.5" the whole way from manifold to tail pipe. Stainless you won't need to replace like thin mild steel tubing many exhaust shops use today.
I'm sure the kit and having the box of bends will cost more and having the parts of the box of bends fabed/welded up to mate/bolt to the manifolds will cost more. than having a run of the mill compressed bent up "custom" pipes.
If It is a cruiser , the shop bent stuff will be fine, but you might be doing it again in a few years when the pipe rust out at the seam. Note if you have a mild steel bent up. ask the installer to try to put the pipe/tubings seam at the top, this will help keep it from rotting out as fast as the moisture that collects when it is cooling will be at the tubings bottom, not the top. with the seam at the top, it won't rot out at the seam.the stainless. cost more. pay once cry once.
I spend the money on vehicles I know I'll be keeping more than 5-10 years. as paying once is still cheaper than paying to have it done twice. I use band clamps at the mufflers. This way if they need replacing for any reason. packing burned out and now louder. or the mufflers you picked are too loud or too quiet. you can swap them out without cutting pipes. Welded in look better, but servicing is harder. band clamps FTW.
Good luck.
But you don't need to run headers to use the kit if you don't like the idea of headers and the upkeep they require. I found if you use good gaskets and stage 8 locking header bolts. then use a ball and socket connection at the collector instead of the 3 bolt flange most headers come with, you don't have lexhaust leak issues. Only issue then is if they hang low and hit speed bumps or driveway inclines.
You can always skip the box of bends, and use the oem front header pipe andcut it to meet the kit then a 2.25 to 2.5" adapter. Assuming the oem front pipe is 2.25"
Unless showing they car and putting mirrors under it, no one but you will know. but the stainless will last a lot longer, and exhaust systems rarely rot out the front pipe from the heat, it is the mid or tail/mufflers that rot out.
Sorry the thing highlighted the whole works after the word note. still learning. computer internet forums. now it is all in bold.
Last edited by CutlassMarc; Jul 17, 2025 at 07:21 AM.
You can get the kit and what they call a box of bends. This will allow any shop that is worth a damn hook the 2.5" mandrel bent system to the oem manifolds. and not need to run headers.
Is it worth it. depends on how you use the car, crimped oem style bends don't flow all that well and a 2.25 pipe with crimp bends is under 2" at the bends.
The 2.5 kit and box of bends will be 2.5" the whole way from manifold to tail pipe. Stainless you won't need to replace like thin mild steel tubing many exhaust shops use today.
I'm sure the kit and having the box of bends will cost more and having the parts of the box of bends fabed/welded up to mate/bolt to the manifolds will cost more. than having a run of the mill compressed bent up "custom" pipes.
If It is a cruiser , the shop bent stuff will be fine, but you might be doing it again in a few years when the pipe rust out at the seam. Note if you have a mild steel bent up. ask the installer to try to put the pipe/tubings seam at the top, this will help keep it from rotting out as fast as the moisture that collects when it is cooling will be at the tubings bottom, not the top. with the seam at the top, it won't rot out at the seam.the stainless. cost more. pay once cry once.
I spend the money on vehicles I know I'll be keeping more than 5-10 years. as paying once is still cheaper than paying to have it done twice. I use band clamps at the mufflers. This way if they need replacing for any reason. packing burned out and now louder. or the mufflers you picked are too loud or too quiet. you can swap them out without cutting pipes. Welded in look better, but servicing is harder. band clamps FTW.
Good luck.
But you don't need to run headers to use the kit if you don't like the idea of headers and the upkeep they require. I found if you use good gaskets and stage 8 locking header bolts. then use a ball and socket connection at the collector instead of the 3 bolt flange most headers come with, you don't have lexhaust leak issues. Only issue then is if they hang low and hit speed bumps or driveway inclines.
You can always skip the box of bends, and use the oem front header pipe andcut it to meet the kit then a 2.25 to 2.5" adapter. Assuming the oem front pipe is 2.25"
Unless showing they car and putting mirrors under it, no one but you will know. but the stainless will last a lot longer, and exhaust systems rarely rot out the front pipe from the heat, it is the mid or tail/mufflers that rot out.
Sorry the thing highlighted the whole works after the word note. still learning. computer internet forums. now it is all in bold.
Yeah I always wanted to go for long tube headers but I saw many people say negative things about headers. The car has already cost a lot of money so I wouldn’t mind paying extra for a better system that would last for a longer time. Are headers that much of a trouble maintaining and so and how much would they affect the exhaust sound?
Yeah I always wanted to go for long tube headers but I saw many people say negative things about headers. The car has already cost a lot of money so I wouldn’t mind paying extra for a better system that would last for a longer time. Are headers that much of a trouble maintaining and so and how much would they affect the exhaust sound?
I've never had issues with headers. But I've never used the 99.99 dollar sets either.
The sound, every engine is different.
Header headaches come mostly from leaks and melting plug wires/boots.
Good gaskets and stage 8 locking header bolts stop the leaking at the head, The collector if I use the 3 bolt flange I use a copper gasket. good hardware grade 8 and two nuts per bolt so it can't loosen .
Cheaper headers the flange at the head and collector are thinner and can be an issue. I since they been available have used ceramic coated headers to keep heat down underhood and then DEI plug wire/boot heat sheilding sleaves.
Only other issue is if the header is tight to the g.m. starters with solnoid on them. and heat soak, adding a ford type on fender fixes that. DEI also makes/ sells a heat sleave for the starter if needed.
I've never had the slow cranking from heat soak , but I've used ceramic coated headers also.
You gain nothing with headers till you are past 3600-4000 rpm. so on a cruiser you gain nothing other than oh, that looks cool . So if you don't need them. save your money.
I've used them mostly because I didn't have factory manifolds for the engine or the ones on it would not work /clear when stuffing the engine in a car it was never installed in. OR the oem manifolds are stupidly $$$ . The manifolds on the 454 core I pulled from a junkyard would not clear in the car, and those that do were 400+ each, at that point, headers . They were not needed on a peanut port truck 454, but I was not paying 800 bucks for iron manifolds.
Last edited by CutlassMarc; Jul 17, 2025 at 08:14 AM.
I've never had issues with headers. But I've never used the 99.99 dollar sets either.
The sound, every engine is different.
Header headaches come mostly from leaks and melting plug wires/boots.
Good gaskets and stage 8 locking header bolts stop the leaking at the head, The collector if I use the 3 bolt flange I use a copper gasket. good hardware grade 8 and two nuts per bolt so it can't loosen .
Cheaper headers the flange at the head and collector are thinner and can be an issue. I since they been available have used ceramic coated headers to keep heat down underhood and then DEI plug wire/boot heat sheilding sleaves.
Only other issue is if the header is tight to the g.m. starters with solnoid on them. and heat soak, adding a ford type on fender fixes that. DEI also makes/ sells a heat sleave for the starter if needed.
I've never had the slow cranking from heat soak , but I've used ceramic coated headers also.
You gain nothing with headers till you are past 3600-4000 rpm. so on a cruiser you gain nothing other than oh, that looks cool . So if you don't need them. save your money.
I've used them mostly because I didn't have factory manifolds for the engine or the ones on it would not work /clear when stuffing the engine in a car it was never installed in. OR the oem manifolds are stupidly $$$ . The manifolds on the 454 core I pulled from a junkyard would not clear in the car, and those that do were 400+ each, at that point, headers . They were not needed on a peanut port truck 454, but I was not paying 800 bucks for iron manifolds.
How to they measure the exhaust size? Do they use the inside diameter or outside? Muffler guy showed me the pipes he would use and it measured 2.25” from the outside and about 2.125 inside
Personally I'd go with choice C, the mandrel bent 2.5" kit with the Pypes down tubes that bolt up to the W/Z manifolds. That is, unless you're looking for an excuse to buy headers.
I have to add that ASSUMING you can find a muffler shop that still custom bends systems, these will not be mandrel bends. Also, I've been completely underwhelmed by the workmanship I've seen on friends' cars that had exhaust systems made up by a shop. Nearly all of them use generic hangers instead of the factory style, the joints really suck, and in a couple of cases, the system had fatigue failures and broke on the road because of the poor installation.
Last edited by joe_padavano; Jul 17, 2025 at 11:36 AM.
Yep, I went to the muffler shop thinking stainless mandrel bent exhaust was an option. The thing is no local shop can do that, I will have to go with 2.25" outside diameter traditional. I didn't know however that ii could get down tubes to fit exhaust kits and thought i would have to go with headers since all the kits they sell are header-back. thing is if i'm gonna buy a kit and pay for shipping, customs etc. (I'm not in the USA) I would definitely go all the way on the system once and for all with ceramic coated headers and stainless steel exhaust.
I didn't know however that ii could get down tubes to fit exhaust kits and thought i would have to go with headers since all the kits they sell are header-back.
The 1 7/8 Hooker headers on my car are almost 30 years old. I did have them recoated about 10 years ago.
Quality headers fit well, and don’t leak. I doubt I have touched mine in years. When I had the headers recoated, I cut off the original 3 bolt flanges and welded on V band style clamps. No gaskets, and zero leaks.
Buy good headers, use good hardware and installation methods, and they work well.
Whatever choice you make to be happy, you should know you can paint your whole exhaust system. A good coat of VHT header paint and quality headers are good. They will last many, many years.
"Long tube" headers will make more power over the whole power curve, NOT just 3,600-4,000 RPM's and above.
Similar experience here. Heddman headers that were installed on the 350 in 1990. No leaks or other issues in al those years.
I'm looking to get the Hedman Headers with ceramic coating #58156. It comes with all gaskets accessories, shoul i stick with them or get copper gaskets and locking bolts etc..?
I'm looking to get the Hedman Headers with ceramic coating #58156. It comes with all gaskets accessories, should i stick with them or get copper gaskets and locking bolts etc..?
How do these "locking bolts" lock ? Wouldn't lock washers work ?
I installed a 2.5" 409ss 'header back' kit almost 10 years ago in my '69 442. Ran the Pypes 2.5" stainless downpipes from the W/Z's to the header back system (with H-pipe) and everything fit like a glove. High quality parts that have only turned a light straw color over the years. I recently installed a set of Hooker ceramic coated long tubes so replaced the manifolds and downpipes. Headers fit right up to the stainless exhaust system with no drama. This is a great way to get a good exhaust system on your car and you can upgrade to headers down the road if you still want them.
I'm always a little surprised by the guys who constantly recommend going to a 'local exhaust shop' for a custom exhaust. I wasn't of driving age in the '60's-'70's so maybe things were different then but I can tell you any time I talked with somebody from a local exhaust shop in my neck of the woods, I quickly realized I wouldn't let them do an oil change on my car, let alone remove and install a new exhaust system. Every one around here has closed up shop for good.
As mentioned above, local shops won't mandrel bend anything - especially stainless. The kits available from reputable exhaust manufacturers (Flowmaster, Hooker, Magnaflow, etc.) are the only way to go in my opinion - at least if you're not worried about doing a concourse restoration.
Personally, I’ve never had header seal or bolt loosening with headers over the 45 years and different brands & car makes. Generally want to buy good quality, use better than supplied gaskets & tighten correctly, not way too tight or loose. In a few different cases over time, I doubled gaskets.
I actually have my first ever cheapo headers on SBC el Camino. They are as good any I’ve had, nice flanges, good fit, NOT ONE thing to move or remove for install, seal up perfectly. Remflex flange gaskets. This unfortunately is not directly applicable to Olds. If I knew they would be so good, I would have bought the stainless version.
Instead I bought bare headers, fit them, welded in O2 bungs & gave them to the local coating biz. THIS can be applicable to Olds.
I like the idea of downtubes, however shipping relatively big parts to where i'm from will take some time and cost quite extra. I will go all the way once and for all with Hedman Street ceramic coated headers and a true dual 2.5" 409ss mandrel bent from exhaust from Summit. The kit comes with Summit turbo mufflers but I prefer a quieter muffler since I live in a mountainous area and I don't want the car to wake up the whole town so I'm going with Dynomax Super Turbos.
Last edited by Andrew Anatian; Jul 24, 2025 at 12:00 PM.
Reason: spelling
