My standard cab long bed 91 Ram w250 has the manual transmission and original 360. Its completely stock, no lift.

I am getting close to doing a full tune up and timing chain/wp/crank seals, oil pump and pan gasket, and TB rebuild and intake manifold removal and cleanup and new gaskets, and new valve cover gaskets.

I will deleting the smog pump and I was just planning on welding up any air injection ports on the manifolds. I've fully and cleanly deleted the air injection on a 86 Ford F250 460, so Im familiar with the general idea and process on what's involved.

Thats when I started thinking about headers. I found a cheap set of Hooker Competition Headers 5902HKR on summit racing. (https://www.summitracing.com/parts/hok-5902hkr/overview/)
The reviews are generally good, but they all talk about fitment and ease of installation, they do not mention anything about power increase/decrease.

The headers are only $225 for the pair with gaskets and hardware included. If I use these, I can cut the o2 sensor bung off the old exhaust and install it on one of the headers, or the new exhaust. The catalytic converter will be deleted in the process. This is ok, because my O2 sensor is upstream anyways.

$225 is not bad, a couple of extra shifts at the restaurant. But, I will also have to pay for an exhaust shop to connect my current exhaust (minus Catalytic converter)probably around $150, or go all out and have them install a dual exhaust(probably around $800 with cheopo mufflers at the local shop). If I go single exhaust, my total price will be around $375, While dual exhaust with new mufflers I'd be looking at around $1000.

Will I see any gains on my vehicle with headers? Will the increase gain will dual exhaust? Are the gains worth the price?

My opinion is to not use the headers. The TBI system is extra finicky and does not major changes improving volumetric efficiency. Gains are not worth the price

You need to block the air injection ports on the heads- the headers will not cover them in most cases

Those headers are mild steel- rust city

3 inch single exhaust will be as effective as dual exhaust

see ramchargercentral.com

thanks for the input, I didn't know the air injection system went into the heads.. the air injection tubes on the ford 460 that i removed went straight into the exhaust manifolds, removing/sealing them was easy..

With those headers I was planning on re-coating them with high temp vht exhaust paint.

I was thinking the weight savings alone from switching to headers would be beneficial..

I've got an exhaust leak too so the manifolds have to come off anyways, but if there's no gains worth the $225 headers and the new piping to existing exhaust, then Ill probably pass. But then again, the truck has 180k, and getting the exhaust manifolds off and the collector bolts/studs off may result in me being infuriated and throwing them away.. we'll see

Unlike today's modern cars where $2000 worth of exhaust system will gain you 5hp if you are lucky.
Before the 90's header and exhaust upgrades were always huge gains for me.

I know it's not a truck TBI but I had a 76 Volare Road Runner 360 2 barrel. With 1 modification, headers and duals. It went form a 16.54 to a 15.81.

Just for sound alone I'd do the headers and duals.

Blocking the air ports in the heads is a piece of cake. Just tap the holes and plug with set screws.

So often I hear from NON performance guys that claim that their exhaust manifolds flow just as good as headers.
They do not. Not at all.
Vehicles come with them for several reasons and NONE of those reasons has anything to do with performance. Cheap to make, durable and long lasting...those are the benefits to an automaker.
Tests have been done for years on the benefits of tubular headers on all sorts of engines. The engines with headers always make more power. The more radical the engine, the greater difference in power. It isn't just a matter of headers have greater internal volume and less restriction. It is the scavenging effect that occurs at the point where 4 pipes merge in the collector.
A ballpark guess is 15-20 HP on a 300 HP engine. I've read dyno sheets for years on Mopar crate engines, rebuilt stock Mopar 340/383/440 engines, small block Chevy, you name it.
A single 3" pipe is easier but will not sound as good.

I installed a cheap set of dynomax 1 5/8 primary long tubes on my otherwise bone stock 86 w250 360 4bbl along with dual 2 1/2 exhaust and the result was better than I expected. It added a few hundred more rpm of usable power along with a noticeable increase of power almost everywhere. I can't see any reason why your TBI 360 won't experience similar gains.

Gains to be made? Sure. If you had a carb and could jet up to deliver more fuel to match the added air the motor moves.

However, that's obd-1 EFI correct? There's no tuning available for them. Be careful when you start increasing efficiency. You may cause it to go lean at WOT.

A lot of inference here.

First off, you really can't tune a stock TBI setup to accommodate added fuel requirements.

Second, the "header effect" is less pronounce the milder the engine is.

Third, the broomstick of a cam in a stock TBI 360 will not allow much improvement in power.

Finally, an engine's power output is the sum of it's parts. the stock TBI system will not allow much increase.

Years ago I helped a buddy redo his 89 1 ton with the same engine. After much research we decided the stock 340 cam was about as hot a cam as the TBI system would accommodate and it did. If we had added headers we would have been outside the OBD1 systems ability to adjust for. Did the bigger cam help? Maybe, but it wasn't much. If he hadn't needed a new cam anyway the original roller would have stayed.

There is the problem of the rusting of those thin walled mild steel headers.

The other problem is that at 31 inches of primary pipe length
they are a bit too short for good torque boost for day-to-day street driving.
Your 360 needs minimum 38 inch primaries on 4 into 1 design headers,
and up to mid forties would be even better.

If you are adventurous you might buy those cheap headers along with six 2 into 1 Y's and some additional pipe. Build some long Tri-Y headers for street driving.

SuperCuda now you got me thinking of doing the tbi to carb swap. I did some research and its allot easier with a 4x4.

I will have the engine torn down to the long block when I do everything else, would be perfect time

Thanks for the heads up with the primary tube length, I didnt even look at that when I was checking them out

Just don't be in too big a hurry to tap the heads, because taps are brittle and if you break it off in the hole they are not easy to remove

I know where a pair of rebuilt 1990 360 truck heads are in Tacoma that have 7 of those holes plugged and 1 with a broken tap still there. They are not mine...now. But could be yours if you want to do some trading.

The only good thing about having a tap broken off in an AIR hole is that it helps anchor the JB Weld. Yup, that's my late model 318. On mine I got the correct size drill for the 1/4-20 tap and drilled out all the holes first. Looking back I didn't need to drill the whole length, just long enough to get the tap in far enough to get threads for the bolt.

I am convinced that JB Weld would be the only thing needed to plug all of the holes. No need to tap, although the need to drill or otherwise clean out the holes would still be there.

RE: headers or not...Headers will get you more torque before the torque peak as well as after. The length issue isn't as dreadful as it seems. The suggestion to turn the headers into Tri-Ys is sound. You'd have to walk through the pairings, though.

About tuning - you are in the Seattle area and except for the moisture in the air, you have pretty dense air year-round. So you could run out of fuel or the computer might run off the edge of its adjustment map and go into limp-home mode. I think the easiest thing to do would be increase fuel line pressure. I'd start with 5psi.

It is against a federal law for a shop to remove a catalytic converter and build a new exhaust system without one. Maybe the shops are ignoring this law, but it is on the books. Without a converter on the car, you'd flunk the visual check and would never make it on the dyno for an emissions test. A high flow converter isn't a bottleneck for a <300hp engine.

R.

youre assuming the TBI setup is tuned perfectly to the components already installed and that its not already running rich and there may be no added fuel requirements

In our state we have a rolling 25 year limit on testing and a 1991 model won't need to be tested. I know about the laws and actually had gone through that with another truck that I had. It was a 1989 Chev 1 ton dually with a TBI injected 454. The Midas shop made it pass emissions with two new cats...it was still a POS and spun a rod bearing shortly after that...I will never own another Chev

My stock 360 magnum motor transplant was converted to a 600 Holley, M-1 dual plane, headers, 2 1/4" duals, 3.91 gear. In my 82 2wd D150 long bed w/fiberglass topper and stock auto ran 14.90s
Doug

In 75? I installed long tube headers in a Ford full size Ecoline van with a 302, to improve gas mileage (1st gas crisis), seems like it improved a lot, like 20%, I was hooked. I did tje same to all sorts of work vehicles over the years, always saw some improvement, but starting with the efi stuff, not so much, and I took them off my current 400K Tacoma. In your case, it still might be worth it.

I assume nothing other than it's not running pig rich as is. IOW that it is running properly and the OP wants more.

If it is running too rich then FIX IT first, otherwise quit wasting our time.

I've messed with these systems back when they were "new" and they were limited out of the box. No one I know of can tweak the computer to compensate and there are some that try to crutch it with fuel pressure increases. That sort of works at WOT at the expense of everywhere else.

Well, I think to make just clean, re-freshen everything outside the long block for now. If it will take a carbureted set-up or different tbi/efi setup with a a different or afermarket ecm to make a proper foundation for medium power gains, then Ill probably just treat my stock engine to a freshen up (outside the longblock) and use it till I can afford to do a tbi to carb swap and get some headwork done and a cam swap, or grab a magnum 360 and computer from a 93 ram