Manifold or Headers, H or X pipe, muffler brand

[FatherandSon]

I just installed new GMPP 350/290hp in my stock 69 C20 daily driver. Right now it has the stock manifold to single pipe/muffler exhaust. GMPP installation specs say best exhaust for engine is long tube headers with 1 3/4" primary & 3" collector to 2 1/2" pipe w/H pipe. My goal like most is to make it sound nice & improve performance but not spend a lot. Unfortunately, I know little about exhaust systems.

Here are my concerns/questions:
1. Most headers available are 1 1/2" tube. A Super Chevy article indicated a 1 5/8" tube is best & can produce up to 16 hp but larger tubes drain low end torque. GMPP says 1 3/4" is best. Does the 1/4" or 1/8" make much difference?
2. A lot of posts on this board indicate a strong preference for stock manifold over problems w/headers. Will I notice the increase in hp w/headers or be wasting my money?
3. Several posts indicate a preference for X pipes over H pipes for sound quality but some indicate this may reduce low end torque by reducing back pressure. Which is best?
4. Which mufflers? Are Magnaflo & Flowmaster worth the price or is there a quality lower cost option?

[chevytruckluver]

I wouldn't get too hung up over a SC article, you wont notice 16 hp.
1. buy a good brand header with a thick flange.
2. exhaust systems can cost a lot, they are worth it if the motor is built to produce lots of hp. the engine you have, you probably wouldn't feel much difference in a C10.
3. The H pipe for tone balance and torque
4. Personal preference here on a daily driver, if you listen to a radio you wont want Flowmasters

[jessemthompson]

You will notice a big difference with long tube headers over manifolds. 1 5/8" will be plenty for your primary size. As far as an X pipe or an H pipe. It's personal preference and just about everyone has an opinion on what they prefer. Mufflers are also preference. I am usually a flowmaster guy, but have a set of spin techs for the project I'm working on now.

[tommys72]

I just put flowmaster super 44s on mine about 2 weeks ago. Sounds better every time I drive it now. Stock manifolds, 2 inch duals all the way back behind rear tires. Sounds great! And I can hear the radio just fine.

[MikeB]

Originally Posted by FatherandSon

1. Most headers available are 1 1/2" tube. A Super Chevy article indicated a 1 5/8" tube is best & can produce up to 16 hp but larger tubes drain low end torque. GMPP says 1 3/4" is best. Does the 1/4" or 1/8" make much difference?

That's nuts for them to say 1-3/4" is best for that engine. Both 1-1/2" and 1-5/8" will work better. 1-1/2"may give you more spark plug & boot clearance.

2. A lot of posts on this board indicate a strong preference for stock manifold over problems w/headers. Will I notice the increase in hp w/headers or be wasting my money?

I'd say your rams horns will work great with that engine. I pulled some troublesome headers off my 69's mild 383, and went back to my angled 2" rams horns. Gotta say I didn't notice any seat of the pants power difference. Properly sized headers always help a little throughout the power band, but can be a PITA depending on how well they are made.

3. Several posts indicate a preference for X pipes over H pipes for sound quality but some indicate this may reduce low end torque by reducing back pressure. Which is best?

Back pressure increases torque just like cheeseburgers make your heart healthier.

4. Which mufflers? Are Magnaflo & Flowmaster worth the price or is there a quality lower cost option?

IMO, both of those will be very loud, except for maybe the long case 70-series Flowmasters. Dynomax long case Super Turbos are quieter and cost less.

[FatherandSon]

Thanks for the replies all. Good food for thought. Any more opinions on muffler brand? I found some info that indicates Flowmaster and Magnaflo may not be the best choice/restrict more than other brands that cost less.

[Mmorgan32]

I have the same engine as you I have stock manifolds for 2 reasons, I have my engine set up to look completely stock, and I get tired of changing header gaskets its a pain I. The ass and with this engine you won't notice the hp anyways, the ticking of a leaky header gasket drives me insane. I have true duals, h pipe and 40 series flows my truck sounds amazing not super loud at idle but when I hit the gas it sounds like a muscle truck which in my opinion that's what these trucks are supposed to sound like. I live in Fresno where it's over 100 degrees everyday I drive with the windows down and I just turn the radio up louder. Personally I think magnaflows sound terrible on old trucks. Oh my whole system cost $425 out the door mandril bent and all welds no clamps

[FatherandSon]

What's the deal with leaky headers? I've read a lot of posts about this on this board. Is this due to thin flanges or is there something unique to our engine/truck set-up that contributes to this?

[elkniks]

A decent set of headers with good quality gaskets and fasteners will not leak on you. I have not touched my headers in 15 years. No leaks.

[Mmorgan32]

Its due to buying a set of $2-300 headers instead of $600.

[FatherandSon]

Good to hear elkniks. What type of gasket did you use if you recall? Is it reinforced felt, copper, aluminum...

[BossHogg69]

I'm using Hedman Elite Hedders on the BB in my '69, and they are nice. They have thick flanges, thick tubes and are coated. I wouldn't even mess with an uncoated header, but that's my opinion. They start looking crappy pretty fast. I'm using 3" pipes, an H-pipe and Borla XR-1 mufflers. They are loud as hell at idle and are deafening at WOT. It's not my daily driver.

On the daily driven small block equipped trucks I've had, I like 40 series Flowmasters or Flowtech Terminators. I've also had headers on every daily driven truck I've had and used copper gaskets and NEVER had an issue. The only leak I've ever had was from using a paper header gasket, and that only happened once. Anyhow, both of those mufflers are loud when you get on it, but not annoying at idle or cruising - but I like loud pipes. I've used H-pipes and X pipes, to me there really isn't much difference. The H pipes are a little more boomy/more bass, the x pipe is a little more high pitched and raspy. Mufflers also have a huge effect too, personal preference I guess. I currently have an x pipe with stainless long tube headers & 2.5" duals with Flowtech Terminators on the '05 GMC in my sig - it also has no cats on it and sounds like a hotrod.

If I were you I'd do some nice coated 1 5/8" long tube headers & get some copper header gaskets. Throw away the paper gaskets that will most likely come with the headers you buy. Then true duals, and maybe an H-pipe, since to me (just my opinion!) they're easier to package under these trucks and some Flowmasters. I probably wouldn't even worry with the H pipe, as I don't know if you'll see much of a gain, but it's just cool to say you have one. I just like the way Flowmasters sound on Gen I small blocks.

[FatherandSon]

Thanks Mmorgan 32. That's what I was wondering w/respect to flange thickness. I have a 69 custom camper special and lean heavy stock as well. It still has factory paint/patina, white wheels and oem caps. I usually stick to if it ain't broke don't fix it, so sticking w/manifold is definitely attractive. Although I did go hei for reliability and would like a little thump in the exhaust.

[FatherandSon]

Thanks BossHogg69. Copper sound like good advice from what I've read elsewhere. I may decide to bring it down to hot rod rake not slammed in the future. Any idea if standard long tube headers for my C20 present a clearance problem?

[special-K]

I have headers on my '72 that were installed in '04. I have never had to replace a gasket or even tighten the bolts. They have outlasted the exhaust because one side rusted apart behind the muffler and I had to fix that. The mufflers are Flowmaster and are not too loud for a radio. It's been so long I'm not sure which ones. I've never used an H or an X pipe so I guess I don't know what I'm lacking, because my trucks have always run great and done what I need. I use them to haul, so I don't think it matters enough to argue.

[Elliot949]

On a low horsepower motor you are not going to see a huge difference in HP or Torque between Headers and manifolds so go with what you like the looks off...

I assume with a 350/290hp you aren't drag racing it anyway... JMHO

[special-K]

290hp is respectable power. My how jaded we've become

[swamp rat]

Search a horse power VS pipe diameter flow chart for exhaust pipe and you'll find that for you horse power you won't need anything more than stock manifolds and a 2 1/4 exhaust duals

[GASoline71]

Originally Posted by special-K

I have headers on my '72 that were installed in '04. I have never had to replace a gasket or even tighten the bolts. They have outlasted the exhaust because one side rusted apart behind the muffler and I had to fix that. The mufflers are Flowmaster and are not too loud for a radio. It's been so long I'm not sure which ones. I've never used an H or an X pipe so I guess I don't know what I'm lacking, because my trucks have always run great and done what I need. I use them to haul, so I don't think it matters enough to argue.

I agree with this 110%... I have had headers on dang near every rig I have ever owned and have never had the problems that everyone claims to have with headers. From $150 dollar Black-Jack cheapies to $700 dollar Hooker ceramic coated jobbers. Main thing... don't over tighten fasteners. Warped and bent flanges from over tightening bolts blow out gaskets.

Originally Posted by special-K

290hp is respectable power. My how jaded we've become

Boy haven't we. Just like everyone nowadays is scared to run an engine on the highway at 3,000 RPM's because it's "too high". Modern Fuel Injection and modern overdrive transmissions have really spoiled us.

Gary

[special-K]

^^^ Amen. Makes me wonder how I drove cross country and crissy-crossy all over America in old trucks. I'm sure glad nobody ever told me I couldn't do it cuz those were the best times of my life. People now complain about mufflers that drone. To me, anything with O/D drones at such a low rpm. I love the sound of a truck running 3k or better all day long.

The main thing is use quality crush gaskets and not that paper crap. But, I have had pretty good service even from those. I always doubled up the paper collector gaskets. My experience, and I know they are old cast iron now, has been broke or exploded stock manifolds and leaking donut gaskets. I hate dealing with exhaust manifold studs, too. Is there anyone who does? You can get to collector bolts easy and for me I prefer my plug wires over the top and easy to get to rather than tucked under the manifolds. To each their own and that's my take on it. I've never had headers hurt performance in any noticeable way where they weren't required